I can remember Geoff Hamilton say on Gardener's World that he had the same problem.I also think that growing conditions can make a big difference to the size of plants.
I find that I have a similar problem when it comes to biscuits.How many packets to buy in order to replenish the biscuit tin?And then there is the dilemma of the BOGOFs.At least with biscuits, the few that refuse to be crammed into the tin can easily be found a home. Just make sure that the crumbs are all wiped up...
I also think that growing conditions can make a big difference to the size of plants.
A garden is an oasis for creation, available to anyone with a little space and the compunction to get their hands dirty.