I really keep wanting to mark files as "reviewed" in a PR.  heres why:

• It shows me how far I've come and I get a sense of accomplishment
• I don't re-review the same files over and over again by accident.  If changes are made to the PR to a file I've marked as reviewed, it should auto-uncheck
• The reviewee sees my progress and knows that I'm actively working on the review
• If I come back to a review, I can more easily get right back to the spot I was at in the review without scrolling excessively