the thing of it is, most places charge you one setup fee... you don't have to pay extra for getting more sizes, so there is no reason not to get the XXXL and the XS. I know developers come in both sizes, and as so many other people in this thread have said, people, generally speaking, have a preferred T shirt fit, and if the T shirt doesn't fit that way, they won't wear it.
If you are buying for employees, it's easy enough to ask employees what their preferred sizes are. We all have a few tradeshow T-shirts at home, so we know how the various sizes of various brands fit us.
Buy some extra; some people will want two, if you have leftovers, mix them in with the next iteration, or leave them on the 'free' shelf in the break room, you know, for when your employees feel like upgrading out of their old copy that has developed holes.
If you are buying for the general public, well, you plan to run out, right? it doesn't really matter if you run out of the big sizes before the little sizes. keep track of what runs out of last and adjust accordingly next time.
If you end up taking home leftovers, mix them in with the next batch of shirts you give away.
If you are buying for employees, it's easy enough to ask employees what their preferred sizes are. We all have a few tradeshow T-shirts at home, so we know how the various sizes of various brands fit us.
Buy some extra; some people will want two, if you have leftovers, mix them in with the next iteration, or leave them on the 'free' shelf in the break room, you know, for when your employees feel like upgrading out of their old copy that has developed holes.
If you are buying for the general public, well, you plan to run out, right? it doesn't really matter if you run out of the big sizes before the little sizes. keep track of what runs out of last and adjust accordingly next time.
If you end up taking home leftovers, mix them in with the next batch of shirts you give away.