You mean, so you can 1) mug the cardholder, and 2) try all the 4x4 combinations (or 5x5 for mine), which I believe will get the card eaten after a small number

You mean, so you can 1) mug the cardholder, and 2) try all the 4x4 combinations (or 5x5 for mine), which I believe will get the card eaten after a small number of failures? Seems like it would be much useful for snooping pinpad door lock codes, which often don't seem to care how many errors you enter in a short period.