How many confirmations do you really need for micropayments? I just ordered a pizza and it went through almost instantly without paying mining fees. Bitpay saw

How many confirmations do you really need for micropayments? I just ordered a pizza and it went through almost instantly without paying mining fees. Bitpay saw the transaction on the network and knows I'm not going to try double spending 15 EUR. EDIT To expand on that: the longer block times can actually be an advantage because the probability of orphans is smaller. If my transaction ends up in some orphaned block and is not resend the merchant won't get any money.