TV and radio both use what is called a "Flex Clock," with approx. (flexible)times slotted for commercial breaks in each hour. Usually, the first break is at :10 or :18 minutes past the hour, then again at the bottom of the hour, at :40 mins, then finally a break at :50. In TV they often have a final break just before the top of the hour at the end of the show.
I’ve noticed with Fox News that the evening shows have a commercial break for about 3 minutes starting at 55 or 56 minutes after the hour, then come back for a minute or two of the original program, then move right into the next program without a break. I assume that is to keep as many viewers as possible for the next show—if there was a commercial break at that point they would lose a lot of them.