I could say "I feel like I spent all day doing code reviews," meaning that I probably did other things too, but the volume of code reviews was draining, so the small amount of other things that I did were less noticable.

Using "feel like" in that context is accompanying the hyperbole that follows. The mods aren't literally fighting a torrent of spam/bad content, but there probably is a lot of it, so it "feels" more extreme