> The general rule of thumb I’ve encountered is closer to 100 - 150 pages.

Practically all novels I've gotten to page 50 on I've finished. The only book I ever made it anywhere close to page 150 without getting anything back was The Fellowship of the Ring, and I think I got to page 200 before giving up (because I felt that I should be a person who liked The Lord of the Rings). It was a grueling experience. I can't fathom putting in 100 pages of joyless reading on a regular basis.