Why is it that filming 12 episodes of a show in the UK always sounds like a monumental, exhausting task? Is there something different about it from US productions?
I was thinking the same thing but it's not really uncommon in the US depending on the show. Always Sunny in Philadelphia, Ash vs. the Evil Dead, Rick & Morty, and Archer are all examples, to varying degrees, of shows that run for a shorter season a year. I mean, for a science fiction show, I can see where you're coming from. Star Trek, Stargate, Battlestar Galactica, and other shows always about 20 episodes a season.
I was even reading up on the history of Doctor Who and the old shows in the 60s ran from week to week throughout most of the year.
I'd think for an actor, cast/crew, writers ... the more demand for work with little to short gap is a blessing. You come back after a year to shoot a half dozen episodes and you might lose focus on what you're doing.