VBD2 is closed. Please go to https://vbd3.co.uk instead.

As a volume seller (over 7000 feedback now) we have automatic feedback setup. The system leaves positive feedback the second it is received.
For those who do not leave feedback, we wait a month. If they haven't complained by then, they must have received the item satisfactory. So we leave them feedback and 80% of the time they reciprocate.

As a seller, I leave feedback for the buyer at the same time I print the shipping label (well, right after I print the label). Not every buyer leaves feedback and it does make you worry if everything is OK. I check on every package, one week after it was sent, to make sure it was delivered. If the buyer does not leave feedback, I do not intrude upon them to ask questions or to ask for feedback. If there is a problem, I would hope any buyer would contact me for a resolution but I am not going to invade their privacy to ask for feedback.