Nic,
I have several old timers with various Swiss chronograph
movements (Valjoux, Landeron, Excelsior Park, Venus,
Junghans, etc). In the past I needed to regulate them with a
stopwatch which took hours to get a meaningful reading and
then hours more to see if the correction was an improvement.

Then I discovered the, economical for a hobbyist, electronic timer
by Microset. I can now do quick time adjusting either with or without a
computer. Because of this device I can keep my old
guys within 10 seconds a day unless they are inherently erratic
from wear or grime. Take a look at the link and just for fun here are
some pics of those I keep accurate.