Some camera/lens combinations are very stable. Others drift over time and/or changing environmental conditions.
Our suggestion is to re-test after 2 weeks or so. If the AF adjustment remains stable, let it go to a month or two before testing again. You will need to establish what works best for your specific gear, shooting schedule, and environmental conditions.
When approaching an importantl session, where focus will be critical (wide aperture and/or close range), we would suggest to do a LensAlign check before the session.
It is also a good idea to re-test when leaving for or returning from a trip.
Over time you should be able to determine the stability of your lenses and camera bodies, and create a proper testing regimen that meets your needs. For some people this might be once a year, and for others, it might mean before every session. It is a personal decision based on your gear and your needs.