For me, it's more about how much I enjoyed the experience than a simple dollars per hour equation or something. It's a very case by case basis for me.

I remember when Alien:Isolation came out, I told people I got my money's worth in just the first hour from how scared shitless I was the first few times the xenomorph came out to hunt you.

On the other side, I got Starfield for $20 off in the release week, but despite how many hours you can sink into that game, I found the entire experience rather bland and dull and regret buying it.