Yeah, Jerry Seinfeld has a whole bit about that, I think it's on his I'm Telling You for the Last Time cd. "Oh no, they're not going to wrap this up in time!"
I like how TV Tropolis has been handling Married with Children, they've kept the Sinatra sung theme song you can't get on the DVDs and they don't put an ad break in after the opening credits and before the first act starts. All channels should take that kind of consideration but money, specifically the advertising dollar comes before everything.
It's why I love tv show DVDs and bit torrent stuff, no ads, but you see the few seconds of black when there's an act break so there's still the same pacing as the show's orginal airing and if need be, it's when I pause the DVD to go get something or take care of something.