I leave them feedback as soon as they pay, which is what you are supposed to do.
Yes, I just assume they recived it ok unless I here otherwise.
I couldn't really care if they can be bothered tp leave me feedback or not.
Over my 3 accounts I see I have left a total of 14,341 feedbacks and only received 11,996

Feedback as buyer isnt much better. I leave it when I receive the item. Many sellers never leave it including a number on this bb!
I have 35 purchases made during 2013 which did not receive feedback.