That's not exactly the 10-second rule I was thinking of - and yes, I use that one too!
I cut this off even before going to the grocery store by making a list and only buying things on the list. So if there's no junk food on the list, I don't even go down that aisle. For impulse buys at other stores, I generally ask myself "Do I really
need this?". Nine times out of ten, the answer is no.