It still is the unofficial norm - around 41 minutes of program, 19 minutes of non-program. MOST shows in Crime Time hold pretty close to that ratio. There are exceptions, of course.
I tend to rent DVD sets of hit TV series, and shows like CSI and "24" normally run 41 - 41:30 of program per episode. An exception was the first ep of Season Two of "24" which ran something like 53 minutes. Fox gave up a lot of avails (commercial time) to hook the audience into the beginning of that season. They probably did the same with Ep 1 of Season Three, the current one.
TV shows are GREAT on DVD, being completely devoid of commercials and promos. Oh, they still go to black where the inserts are made, but a second later the show starts up again. With a show like "24," you can watch the entire 24-episode season in just a few viewing sessions. An entire DVD of 4 eps lasts less than 3 hours, a typical long movie. Plus the video and audio quality is better.
Michael
They've done the first ep. of each season "commercial-free", though they did a long commercial spot before and after the show. It was very easy to get hooked on 24 in season 1 with a very movie-like first episode without all of the commercials.
24 is great on DVD. (As is Babylon 5, Firefly, Farscape, ...)
I bought Friends Series One on DVD and really liked it. I missed most of King of Queens. I concur with your assessment of tv shows on DVD. I could care less about commercials.