For series the episodes are written with commercial breaks in mind. For example a typical "The Simpsons" episode is written as 3 acts and the commercials come between the acts.
Movies aren't written with ads in mind, but usually the cable channel running the movie takes into account what is going on in the movie when they decide where to place their ad breaks.
This makes that ads a lot less intrusive than ads on YouTube or most other ad supported streaming services.
With the ads not actually interrupting the story, they actually often provide a convenient break to get up and get a snack, or clean up after the last snack, or visit the restroom. And I can always pick up my iPad or Kindle or a book to pass the time during the ad break if I don't need to do any of those other things.
We can argue about how pervasive advertising is and how subtle it can be, but cable TV literally has commercial ad breaks.