is fine for me, if it is slower or faster, than i think i will regulate it or service the movement.

I almost never wear a watch longer than three or four days in a row. So it doesn't bother me if it is running a bit too fast or slow. If it looses 1 minute every 3 days, it's on the edge.

My experience with cal 12 is that they can be running very precisely, almost within chronometer standards.

juko