Well it depends. Some shows will have limited commercials; usually a 30 min show will have about 2 commercial breaks lasting a total of around 7-10 minutes. Live events like Basketball, or American football have a lot of breaks, but they are short breaks (30 seconds) between timeouts and standard timed breaks during the end of a quarter.
As far as the WWE is concerned, I don't know why they cut into the match, could be a ploy to get you to see a live event, or they just want more money, or a lot of companies want to run ads during Raw. Whatever the reason, it can be bothersome, but I've gotten use to it, plus I usually record it or catch it online since I'm not always home to catch it live.