Users like whuber, Glen_b, gung, Peter, Frank, Jeromy, .... I see your edits, comments and answers everywhere! I was just wondering how much of your time you spend on stats.se? Do you have scheduled hours every day or do you hop in when you find time? I have been lurking for a long time and would really like to contribute to the community which has helped me learn so much. Please share some of your tips on user involvement.
I guess my comments grew long enough for an answer.
Each of those users will have different profles of time spent per day and how it's achieved. Some aren't here so much nowadays but were very active in the past.
For me it varies. I don't work full time atm so I spare a little time each day, but I recently reduced my time here. I do a little when I first wake up or when going to bed, plus ten minutes when I can squeeze it in (e.g. at lunch), or if there wasn't time then, maybe 15 minutes in the late afternoon. Unless I'm busy with other things, more time on the weekends. Some days I don't answer anything, and then it might only be 10 minutes total -- it's more "do something every day" than "spend lots of time". Many edits, reviews or comments can be squeezed into 10-15 minutes; I type quite quickly.
Over a few years, a little time every day adds up to thousands of actions.
A lot of my longer answers have many edits... often that's a case of 'write a 5 minute answer' because that's what time I have spare, then add a paragraph or two later. Maybe I'll come back even later and add a diagram or a reference. It's rare for me to have the time to construct a single long answer in one go. Even when it looks like a one-edit answer, it has often been constructed off-line in several short bursts then posted. (On SO that seems to be regarded as not good practice -- they have an issue with 'fastest gun' answers where people post very short answers quickly to draw early votes that are needed to get an answer noticed and then build it up to a good answer. Recently here we average a good deal less than one answer per question so it's not so much an issue if someone makes an answer in small pieces.)
If you're interested in strategies for generating reputation with moderate time investment, I think a good long term strategy is to check regularly, answer 1 or 2 questions that relate to what you know (i.e. make a few reasonably substantive answers than many short ones) and improve the question in ways that help people find it / makes them want to read it (good titles, appropriate tags, clarity).