I have been, and will continue to adjust seed quantities when I open the seed packets and find out how many are there. I started low - no one will be disappointed that way. (If that bonus pack of Red Merlot Lettuce doesn't have more than 10 seeds to offer, I'll withdraw the offer and plant them all myself!😉)
Those with less swap experience will soon find that offering too few seeds per pack is a good way to get stuck with them.