I like this question and used to think that.. it does seem simple but theres loads of reasons. Just a few here coz im having trouble sleeping. Budget. To keep a consistent quality you have to streamline everything. Even something simple like butchers dog on screen for a season might cost twenty grand for the dog and wranglers over so many days, then you’ve costs in its specialised training for indivual actions, ‘mulitples’ ie dogs on standby just in case, prop dogs for lining up shots and lighting, CGI dog assets and then all the time (money) spent preparing and shooting. That 1 dog in every scene is going to have you behind schedule and over budget day 1. I might do a simple budget breakdown of a boys issue to highlight if i get time.
The other thing is human nature. The first thing your going to do is cast Huey, and thats when you realise a 5’4 bald, pudgy, Scottish git with a goatee and skin like an A4 sheet of paper won’t translate how you’d expect..youre trying to get bums on seats to a show that 98% of people have nver heard of. And when you do cast the perfect Huey, boy is he going to have some suggestions as to what he’d like to input into his character. Suggestions that will change and interpet the character for the perfect Huey might cause friction if you don’t allow him to do his job.
Thats creatives though, and you’ve now got to find a Director willing to have no creative input into the Direction of the show, because its already been laid out. You’ll also be reducing the Camera dept, and its going to take you three times longer to shoot anything because you’ll only need one camera to shoot specifically framed scenes. You might figure that to counter you can shoot muliple Units simultainiously, but once you work out hiring (and finding!) multiple crews with the same quality of work will cost an absolute fortune. In TV you’d usually shoot between 4-8 pages every day with every page reflecting 1 minute of screen time so to shoot a 50 - 60 minute ep will take approx 2 weeks, 8 eps / 16 weeks. You might get through it in double that, and thats not accounting for the big set pieces with lots of cast, costumes, makeup, locations and CGI.