I think S Taylor summed it up well. Take your time and do it right. Everyone is different. I do one a day. Helps having a working wife. After a few years and a good referral base I raised my rates and make a reasonable days pay. 4 hours on 2000 sq ft is not unreasonable. Some I have done in under 3 hours some over 4 hours.
I have spent 8 hours on a 6000 sq ft house.
None of this includes the report that takes me longer than most. (I think it is my software) Not built for speed.
I find most people are very glad I take my time and are very appreciative.
I consistently get positive e-mail feed back and many times have been given bonus money. The gratification of doing a good job and feeling good about your work is big for me.

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Dave