My DH runs an ebay account, kind of...well he doesn't know how to list, he just likes buying stuff in his spare time, then leaves it all to me....and he NEVER leaves feedback. So I usually end up sorting it out in batches for him at the end of every month or 6 weeks.
I might find it frustrating to get a reminder email through, but that's only cos it pricks my guilty conscience! I usually immediately send an extra nice one, again, cos of guilty conscience.
I agree with the sixlostmonkeys that feedback is about to lose all value and I will probably not bother doing any for him from May onwards. What's the point???