Many TV shows start off great and then struggle through That Difficult Second Season. Many series are almost perfect but still dished out a handful of rubbish episodes.
But every now and then, the televisual planets align, and every single episode is either magnificent, or at least... never bad.
Obviously, this is subjective by nature, but we reckon we've narrowed it down some of what we consider – technically – the best TV series ever made considering they never dropped the ball.
The only rules are that we're not considering one-off or limited series (sorry, Band of Brothers), or shows which only had one season (sorry, we want some consistency).
1. Fawlty Towers
You will soon notice a trend that many entries on this list are British sitcoms. This is because the majority of classic UK comedies followed the standard created by John Cleese and Connie Booth: a) keep it short and b) end on a high.
This 1970s sitcom might not have been a massive hit at the time, but it has grown to become one of the all-time greats. With just 12 episodes, Basil Fawlty's angry adventures at the Torquay hotel never had the chance to grow too stale.
Every episode has classic laugh-out-loud moments, from Basil smashing his car with a branch, to the German guests, to the talking moose. Hilarious from start to finish.
2. The Office (UK)
Ricky Gervais and Stephen Merchant have often utilised the Fawlty Towers approach but with a spin: two series and a special. And that's exactly what The Office needed.
While the US version is great in a totally different way, it perhaps went on a tad too long. Its first season was a poor imitation of the original and it got a bit stale after Michael Scott left. And don't get us started about that dodgy 'Farm' episode.
But the original was stellar from the off. You couldn't stay away from Wernham Hogg, whether it was to see David Brent's latest attempt at winning friends, or to find out what pranks were being aimed at Gareth, or whether Tim and Dawn would finally get it on.
3. Game of Thrones (so far)
Unless Game of Thrones suddenly loses it in the seventh season, the HBO drama must surely go down as one of the greatest dramas ever made – certainly the greatest fantasy drama.
You may not be able to name every single episode across its six seasons, and some may have been more entertaining than others, but there has yet to be a genuinely lame entry, and if anything it has just got better with each year.
Providing it has a satisfying conclusion in 2018, Thrones could be a rare TV drama where you can watch from start to finish and it never becomes a chore (we're honestly not looking at you, Walking Dead).
It certainly helps that there has never been over 10 episodes per season. So many great dramas from Lost to The West Wing have suffered from the 'bloated season' problem.
4. Father Ted
It's still heartbreaking whenever we're reminded of Dermot Morgan's death at the age of 45, just a day after the third season of Father Ted had finished filming. Who knows what he could have gone on to achieve and how many more series of the Irish comedy we might have got.
The only solace is that it meant that Father Ted ended on an absolute high. It was never anything less than hilarious, and we're left with 25 episodes of pure joy.
The fact that Father Ted is still repeated on a weekly basis on British telly nearly 20 years after it ended goes to show just how loved this show is, and how it's always a treat when you're channel surfing and land on any episode. The perfect sitcom.
5. The Shield
This FX crime drama from the States is criminally overlooked in lists of the 'greatest ever' shows. But those who have seen it from start to finish know that it was a constantly thrilling look at the shady side of law enforcement.
While other brilliant US TV dramas such as The Wire or The Sopranos are generally fantastic, they still had their moments of disappointments or dull periods, becoming a slog every now and then. The Shield never did.
It's continuing nature never allowed it to get bogged down with boring storylines or irrelevant characters. It always had a goal in mind: just how far could Vic Mackey and his team go before everything around them imploded?
Fast-paced, shocking and captivating, but with a cheeky grin in its back pocket, it's generally considered to have one of the greatest and most satisfying finales of all time.
6. The Inbetweeners
OK, the actors may have been far too old to be playing high-schoolers, but if anything that's what gave The Inbetweeners its certain charm and knowing wit.
It also may have jokes and lines that we doubt they'd get away with using today, but that's another reason it's so enjoyable to binge on. It harks back to a strangely innocent, but not-that-long-ago window before social media took over our entire lives.
In 18 excellent episodes, the show perfectly captured what it was like to be on the fringes of popularity at school in suburbia, with a cast of characters who were born for the roles. Even the movie spin-offs were decent follow-ups, which isn't an easy task.
7. Cracker
From the off, Cracker was something new: a crime drama that was more of a whydunit than a whodunit. Plumbing the darkest parts of the human psyche, Robbie Coltrane's Fitz was a forensic psychiatrist with a drink and authority problem to shame a horde of would-be detectives.
There are 15 perfectly formed stories, each a brilliant balance of thrills, mystery, acerbic wit and profound character study.
8. Modern Family (so far)
If we were going to pick just one US comedy for this list, it would be Modern Family. What, no Friends, you ask? As much as we adore Friends, it did have its poor episodes (we ranked them ALL to prove this), and it perhaps turned its characters into caricatures by the end.
However, Modern Family has stuck to a very strict formula from the beginning, and it has very rarely strayed, if ever. While some may say this is exactly what turns TV shows stale (and maybe it will one day), as long as it keeps a certain standard, you can't go wrong.
Somehow, despite eight seasons and nearly 200 episodes, Modern Family hasn't got boring. The characters are all incredibly rich in personality and the storylines are never too silly.
9. Six Feet Under
On the face of it, Six Feet Under sounds like a terribly depressing and pretentious drama about life, death and love. And yeah, it kinda is. But it does it so well.
Under the watchful eye of creator Alan Ball, Six Feet Under consistently kept a certain wistful and emotional tone throughout its 63 episodes, which is actually a relatively low number when compared to other ensemble US dramas.
Whether you tuned in weekly back in the early 2000s or have binged it in one go in recent years, Six Feet Under never had a mixed season or a crap episode, continuously challenged us, and ended with potentially the greatest finale of all time.
10. Gavin and Stacey
We wouldn't be surprised if James Corden and Ruth Jones brought back Gavin & Stacey one day, but we kinda hope they don't in a way, because it's so damned perfect as it is.
Across three series and a Christmas special, the sitcom never lost its unique charm and friendliness. It remains one of the most down-to-earth and easygoing shows ever made. In many ways, it's a British version of Modern Family – one big collective of folks, all of whom have their own hilarious personalities, and you couldn't have the show without any of them.
Its only fault may be that in time it may become rather dated due to its heavy use of then-current pop culture references or music, but that hasn't exactly harmed shows like Gilmore Girls or The OC in further viewings.
It's a charming and laugh-out-loud comedy that can now surely be named among Fawlty Towers and Father Ted in any list of great UK sitcoms.
