If you check the voltwatch at the END of each flight it tells you what you have immediately after being under actual flight loads. That should tell you if you're ok for more flying.

If you check it before a flight it could possibly give you a false sense of security.

The voltwatch argument will probably still be going on when we're all dead. Another argument is cost. Voltwatch costs about 10 bucks per plane. A loaded voltmeter and lead costs anywhere between 20 and 40 bucks and should be a one time purchase.

I have a loaded voltmeter.
I have a voltwatch or two.
I have a few MPI switches with LED charge indicators built in. These are my favorite.