To be honest, I spend around 1 hour a week promoting my websites! I focus more on content! the engines will pick it up and bam, there is your traffic.... For my webmaster forum I am doing some promotion on other sites, but not much either, am entering page 4 now in google for this term, once i am on page 1, the new members will flow in stable
I basically go overboard and spend all day doing SEO, linkbuilding and other stuff. It's all worth the effort though.