I think the overall advice here is pretty solid. I might add a couple comments:
--- The time budget is extremely sensitive to how much you already know about the subject. If you're generally up on the literature in an area, it is often much easier to isolate the chunks that are genuinely new to you and thereby grok the paper very quickly. In a new field, even several hours to really read a paper might not be enough, depending on how much backtracking you need to do to understand core ideas.
--- In physics, the conventional wisdom (which I agree with) is that the main thing to do when checking out a paper is to look at the figures. These are generally chosen to highlight the most important points of the paper and will often quickly convey what was measured/calculated, how the effect scales, etc.
--- The time budget is extremely sensitive to how much you already know about the subject. If you're generally up on the literature in an area, it is often much easier to isolate the chunks that are genuinely new to you and thereby grok the paper very quickly. In a new field, even several hours to really read a paper might not be enough, depending on how much backtracking you need to do to understand core ideas.
--- In physics, the conventional wisdom (which I agree with) is that the main thing to do when checking out a paper is to look at the figures. These are generally chosen to highlight the most important points of the paper and will often quickly convey what was measured/calculated, how the effect scales, etc.