I don't like to hoard more than one clothing size ahead because I don't want something I absolutely love to go unworn! I've had things happen where my kid outgrew it before the season arrived, or didn't grow and it sat and sat in the closet and I either forgot about it, or by the time the season came around again, they outgrew it...!
I guess that's one big negative about living somewhere with such extreme seasons We get crazy snowstorms in the winter and can go up to 100 degrees fahrenheit in the summer.
However, after scrambling to find good daycare sneakers for LMW at affordable prices (and that aren't screaming pink or purple) I find myself hoarding those! She wears a 4 now and I got her saucony jazzes off of shoebuy.com with an eversave coupon... and I just hoarded size 5 pumas from the piperlime sale... and I'm about to hoard some sauconys in a 6 from zulily!
So I guess cross-seasonal necessities like sneakers for daycare (and probably rain jackets? I still need one for her!), I could potentially hoard every size!