Most of the time they do the trick (when rate limited). Even using a birthday will still stop card thieves from emptying your bank account at an ATM. I'd hazar

Most of the time they do the trick (when rate limited). Even using a birthday will still stop card thieves from emptying your bank account at an ATM. I'd hazard a guess that asking for an 8 digit pin will see lots of people just repeat the first 4 digits again.