Everyone in my area has 1 acre lots. I told my neighbor I would mow and trim his yard for $40 since my yard only takes about 30 to 40 minutes. I didn't count the extended time it took to trim all of their shrubs and trees, haphazardly placed all over their yard. I also didn't count that I would have to break out my 21inch to mow a fair portion of his yard that my 60inch z couldn't reach, because of very low over hanging tree branches. They were literally in my face while seated on my z. It ended up taking me about 1.5 hours. Live and learn I guess. I will have to get more experience in judging time to do a job. Is there a rule of thumb to go by when bidding or just learn by doing?