I've only been here a year so my experience probably isn't worth much. I think the longest period I've gone without a sale was about 5 days, excluding periods when I was only doing auctions or stopped listing altogether. Slow sales come when I have nothing but stale listings up. I've had a couple of periods where I've been a little surprised by the lack of attention to certain new postings but, in truth, it's just noisy data. Some posts get a huge amount of unexpected attention and some get surprisingly little. If I'm only listing eight or so things a week, I can expect that every once in a while, all of those listings are going to coincidentally fall into the group that gets little attention and disappoints. It's more likely to happen when I reach a little higher on prices. My average sale is only around $23. An extra two dollars on price can double my profits in some cases but if I reach for those two dollars, the listing might sit a lot longer.
Generally, I've met my personal eBay goals for the year, with one exception, and I expect to get that by the end of the year. Good luck to you meeting yours.
