If it's a quick thing, I respond quickly. If it's a complicated thing, I respond slowly. If I am answering a technical question, I usually take an hour or more to write, let it sit for an hour and up to four. Then, I revise for 30-60 minutes. Sometimes I let it sit again, and revise again. Most emails don't get this treatment, but what I say needs to be accurate, based in statute and consistent with the tenets of my field. What I tell others may be used as the basis for decisions for years, and may be quoted to the service providers we oversee. It's worth it to take the time. I also tend to use the language I've used in previous emails when writing responses to similar questions. So, I save some time that way.