A senior philosopher elsewhere writes:
Like many readers of this blog, I am frequently asked to referee journal submissions. Though I recommend acceptance only very rarely, I feel duty-bound to work as hard on something I agree to referee as I would on something I read for my own scholarship, trying to puzzle through the details of the central arguments and to figure out exactly where those arguments go wrong (when they do). As a result, I would guess that I usually spend 3 hours on a paper I'm refereeing, though often enough it is more than that, and I generally find myself with about two single-spaced pages worth of comments. I have never served on an editorial board, and so I have never been in a position to see a large number of referee reports. Reports that I've received on my own submissions suggest a wide variation in the time and effort other people put into refereeing. I'd be interested to hear from journal editors and other readers about what they think constitutes a conscientious effort.
My sense is this sounds like a responsible refereeing effort. But it would be useful to hear what others think.