It needs to be done well, of course, but mostly it needs to be done now. Plus screenplays have a lot more preciousness, though probably they shouldn't. With that in mind, we writers would do well not to fret and sweat over every little word we write. I've written both sitcoms and hour dramas. I find the dramas more challenging because the physical and emotional stakes in the stories are generally higher, and also because the staging of events is more complex.
Television is taxing, there's no doubt about it.
You're at close quarters with problematic personalities for long periods of time. The thing you need to realize about television is that it's target marketing. If the target is children, you'd better write children's television. If the target is women 18-34, you have to give them what they want. I have one friend who always finds out if the EP is happily married before he signs on staff.