I can't speak for other installers, but I dislike having to climb over mountains of crap to do my job. IMO, people should get settled in, then worry about TV. Of course, I am the ahole who made the lady empty her PODS box to get her TVs from the very back (for real though, how I am I supposed to make it download if there is no TV to hook it up to? I can't just hook the s-video up to my retinas, you know).
Another jerk actually told me I should supply a TV to check them out until his got there. Then I'd have a service call when he can't figure out how to hook it up. I told him no thanks, but he might get another installer to do it. Not me--- if I have to guarantee something, I am going to hook it up and make sure it works personally.