Many years ago I took pride in emailing everyone who took the time to get in touch with me, and I still do... it just takes me a little longer now as I get so much mail.
If you want to contact me to ask questions, I'll usually get back to you immediately. If it's about a job, I try and hold off on getting back to you if I have a lot of work on my desk to get done, so when I do hit you up it's not a "yeah, I'm happy to do it, but I need a month before I can even start it".
I hate this as a system, but it's the only way I can make things work, short of doubling my prices to half my workload!