I gave a talk last week at Brooklyn College on How to Pull an All-Nighter When You Don't Have To. The talk was about how a number of overachievers like Tesla, Freud, and Balzac didn't restrict their all-nighters like many college students to their university years, but they pulled all-nighters on a regulars basis throughout their careers to maximize the amount of time they devoted to working on their passions.
After a couple of years of doing marketing for my books, I'm not sure that giving readings and talks are good for book sales, which may be the reason why Frederick Seidel never gives readings of his poetry. I even suspect that some authors give readings for pretentious reasons. For example, so they can say things like, "I have reading tonight at _____." or "I just wrapped up my book tour. I went to ___ different cities!"
I may give one more reading at a nearby university - only because I'm passionate about sharing my knowledge of the topic; however, I'm skeptical about the talk's significance on book sales. It may be better to spend those few hours working on the next book or a blog post, which definitely has a positive effect on book sales.