Generally, network programs of one hour will have twenty minutes of commercials. 33%
What I see on cable a lot is low commercial load for the first half hour to get you hooked on the show, then high load for the next hour or more. Having a DVR, though, means not having to watch many commercials.
It’s gotten so bad having to fast forward through commercials on my Tivo that I hardly use it any more. It’s all Netflix and Amazon Prime streaming for me (with the occasional Netflix DVD thrown in for rare titles not in anybody’s streaming catalog).
This is why I never watch a TV show directly. I DVR and then skip over commercials.