[londons_explore]

A paper is only a few pages long usually. A read of a paper takes perhaps half an hour. And in that time, you might even be able to check some references, make a few edits, or drop an email to someone to gather some more results for a figure or two.

Doing this once a week seems very reasonable.

[higeorge13]

Proof reading and correcting typos shouldn’t be considered authoring, but it is what it is.

[dahinds]

A close reading of a scientific paper of any consequence does not take half an hour. These days a published paper may typically be only a few pages but it isn't at all uncommon for the paper to be accompanied by 20-50 pages of supplementary text. When I'm asked to review a paper it takes me the better part of a day, at least. If I were a senior author on that paper that would be the bare minimum that I'd consider an acceptable commitment of effort.

[tokinonagare]

It really depends on the field. @londons_explore is right that a lot of papers in some fields can be read in half an hour, or an hour, and sent back with feedback.