Understand if you buy/sell loads you may miss the odd feedback etc. But was having a look at feedback of some folk we are waiting to hear from, item posted yonks ago, and they have never left any feedback. Not ever, for anyone, good bad or indifferent. Just seems a bit odd to me.
And also, do you wait for feedback before leaving yours? As buyers we leave it as soon as item arrives, as sellers we wait for our buyer to feedback first.