Here's my two cents worth. I do look-ups in my county in TX. I do them as soon as I'm able.Period. I also have limited myself to one cemetery and the 1900 census- that's it. When I'm dealing with another county in my own search, I try look ups; but if I don't get a response in a couple days by e-mail, I contact the local genealogical society with a snail mail letter. I always enclose a SASE and a check for at least $5.00. I write it off as a donation. I'm running about 50-60 % on responses via the internet. Sadly, the two counties I've gotten the least help from with queries are Madison County NY and Lackawanna County PA where my two "main" families lived.