I can actually enlighten folk a bit to how long those programs take to make and some of what goes on behind the scenes, having worked for a trainer who was on tv a lot...
First you have a crew, several camera people, one or more sound people, depending on how big the production is you've got the talent, runners, general fetchy fetchy people of all kinds...
So in that owners house, you have got several camera people, strange new equipment, a sound person, and the talent, and lots more going on outside with trucks full of gear.
Some shots are achieved using cameras fixed to walls etc, depends on how big the house is really.
So long before the trainer/talent gets going, the dog has been stressed out and knackered by the comings and goings of crew.
Then they will be asked to film some 'before' shots and often (certainly for The Dog Whisperer) they will use stooge dogs to wind up the subjects dog, often for several hours before they actually start filming the 'fix'. THis is how you get those 'red zone' behaviours shown on The Dog Whisperer, they had a variety of 'teaser' dogs to rile up the dog they were filming.
In some shows the owner has time to talk to the trainer/talent before hand (this is done for Victoria Stilwells later shows when she had a production role, I think for the Nando Brown/Jo Rosie-Haffenden fronted shows they had video chats with people before meeting them in person, it was definitely not done for Cesar Milans shows, any of them, nor for Dog Borstal, Dogs Behaving Badly etc), in some the talent doesnt meet the dog until a ton of preparatory winding up, teasing, getting 'awful dog behaviour' shots has been done.
By the time the dog is actually 'trained' by the shock/car crash style programs, the dog is actually so stressed and knackered they shut down really quickly, which can be why their approaches seem to work miracles.. the audience having NO idea the dog has been run, faced off against other dogs and stressed out to hell and back by crew, cameras in their faces etc for 5 or 6 hours before hand.
Cesar in Dog Whisperer would actually take the dog without the owner present for several hours before what you see in the screen was filmed - it is my opinion (and not just mine!) that he'd use this time to condition the dog to pair his trademark TSST or backwards heel kick with either the effects of a prong collar correction or a shock collar correction. You do not need to repeat such well timed pairings often to produce the seemingly miraculous reactions to them that you see on the screen, but if you try 'Tssst' or nudging a dog who HASN'T been conditioned to those sounds in that way, you will get either a confused response or no response at all, assuming the dog has no prior reasoning to fear those sounds/actions.
Very often the 'before' behaviours are lured and set up, Dog Borstal did a lot of this with owners intentionally leaving food around for dogs to steal, Dogs Behaving badly does a lot of this as well (and putting members of the public at risk to do so, one reason that 4 dropped the show).
In some cases the 'six weeks later' shots have been nothing of the kind, filmed the day after or even later that same day, as thats cheaper than sending a crew back out to film, or relying on the subject to film it and send it in in time.
In cases where the follow ups genuinely are real time, for example Nando and Jo Rosie Haffendens show where rescue dogs were turned into assistance dogs, behind the scenes there is on going training provided by a local trainer which of course isn't mentioned.
And the bits you almost never hear about outside the industry... the people who dropped successful training programs with a local, non celeb trainer, who were making excellent progress with their dog, to go on a show... and the people who having been on a show and their dog is now worse, having to pay a fortune to have a local trainer/behaviourist come and pick up the pieces and fix the mess the tv trainer has left behind.
Tv trainers are not all bad, but even the good ones struggle (and this is why there are so few good ones, they are battling constantly to show what training is really like, amidst the constraits of cost, timing, audience preference etc and often production teams and tv channels who know nothing about dog training/behaviour)... the bad ones couldn't give a toss, they get their name out there, make a fortune, leave a trail of fucked up dogs in their wake and damage the industry enormously.