Add a NAT value to end of shorter and test 1:end-1 location...if it's beginning, then it'll be bum at first; if end just throw away the extra point.
If it's in between, one or the other should still lead to where there's an inconsistency. Of course, it's possible the whole thing is fouled up by some other mechanism than just being off a point, that's indeterminate from just the data alone although if all are positive that's probably pretty good check.
You could, of course, do crude checks that the start and end times are within the expected range of day(s)/hours to find if there's something really out of whack.
