Good in one way. Pointless in detecting ballots which should have never been accepted.
It will, however, likely detect the more trivial math errors.
“ Pointless in detecting ballots which should have never been accepted.”
However, one of the primary means of fraud has been software systems counting certain ballots multiple times and transposing counts (turning Trump counts into Biden counts). A hand count will discover those forms of fraud - which are the fastest way to manufacture votes or change counts.
It would also tell us exactly how many Ballots had a Biden vote for president and no other votes. If there were, say, 15,000 of those and only a few in the other direction (a vote for Trump and no other votes), that would also be evidence of a corrupted vote.