Plenty of people get bored of a level after playing through it once.

Except again, sexual stimulation is different from general dopamine.

I've never found this to be true. I've been jerking off to mostly the same vanilla pornhub tier cuck and incest shit for the past 15 years and have no desire to go further.

That also depends on how often you use porn to wank and how much you cool down inbetween porn usage. I bet you haven't been watching the exact same videos for 15 years.

It is far more applicable for people who use porn often.

There are certain go-to videos I still use to this day that I've fapped to probably thousands of times.

Yes, but not back to back, after you've watched other stuff and gotten bored of them. Try using the exact same video 1000 times in a row and see if you can still get stimulation from it.