It may seem weird, but I think I've always dealt with this by not bookmarking the page I've ended on when I stop reading. I find it next time by skipping the stuff I understand, and stopping when things are unfamiliar and/or confusing. I find a night of sleep (or some significant time away) to be a good way to passively consolidate what I've read so far.
This has devolved to reading the same section over and over again a few times, but I think that's usually because the author made a logical leap that I had a problem with, or simply that I wasn't as interested in the subject as I thought I was.
That's a really smart trick, it reminds me of trying to learn a musical piece and getting really proficient at the parts that come just before a section I struggle with because I play them the most often.
This has devolved to reading the same section over and over again a few times, but I think that's usually because the author made a logical leap that I had a problem with, or simply that I wasn't as interested in the subject as I thought I was.