After I get over the 2-3 week hump, I'm usually alright for a while. It's worse when you're taggin some hotties and then go dry. Immediately afterwards it's tough cause the memories of that tight, clean, beautiful young poon are fresh in your memories.
But hell, I've been a pretty good sexual camel at times in my life. Plus, as I've learned over the years, no sex is MUCH better than bad sex.