Subscribers can expect to see an average of 4 minutes of ads an hour at around 15 to 30 seconds each

Isn't this a lot? I can't imagine watching a movie and being interrupted every 5 minutes by an ad.

Do they clump them together and play 8 minutes of ads between the two halves of a two hour movie?

I have Peacock and Paramount for certain sports and they do this too. I Don't mind it on Peacock, but the way Paramount does it is absolutely terrible and I'll be canceling my subscription once my yearly special rate expires. Peacock will generally show about 3 minutes of ads then let you watch a whole movie. Paramount seems completely random. Sometimes you'll have 45 seconds of ads, then you might have 3 minutes of ads less than 5 minutes later. They'll regularly have 6+ mins of ads in 30 mins.

This will become the new norm, but I'm not too mad; this is likely part of these companies preparing to accommodate the writers and actors to end the strike, the ad revenue will be used to pay residuals.