It varies a lot between papers (in my experience) and between fields (I imagine), but several hours for a deep reading doesn’t seem out of line. To take an anecdote, I was recently re-reading a paper (of comparable length, though in economics) that I’m planning to present as a guest of a mathematics reading group, and I probably spent 4 hours on the re-read, before starting on my slides and presumably re-re-reading a bunch more.
Grazing over several days (and/or multiple separate readings) is also my usual practice for a close read, fwiw.
It varies a lot between papers (in my experience) and between fields (I imagine), but several hours for a deep reading doesn’t seem out of line. To take an anecdote, I was recently re-reading a paper (of comparable length, though in economics) that I’m planning to present as a guest of a mathematics reading group, and I probably spent 4 hours on the re-read, before starting on my slides and presumably re-re-reading a bunch more.
Grazing over several days (and/or multiple separate readings) is also my usual practice for a close read, fwiw.