I have a tiny channel that posts long (3-4 hours) gameplay videos and premium is 80% of my revenue. I do have mid-rolls and unskippable ads turned off, but in my experience those would only increase my ad revenue by 10-20%, i.e. premium would still be ~77% of my revenue. For reference the average view duration for my videos is ~25 minutes (premium pays by total watch time).

https://i.imgur.com/wqE2QJ2.png