A standard maintenance visit - spring tension check, roller and track inspection, lubrication, opener force and sensor check - doesn't take your garage out of service for an extended stretch. You can plan around it rather than work your day around it.
Where it gets longer is if that visit turns up a spring that's near the end of its life on a door this old. We're not going to put a worn spring back together and call it maintained; if it needs replacing, we replace it while we're there rather than scheduling a second trip, which is better for you even though it extends that particular appointment.
Homewood homes built around the 1970 median are old enough now that this crossover - maintenance turning into a parts replacement - comes up more often here than in neighborhoods built after 1990. It's not a sign anything was done wrong originally. It's just what 50-plus years on the same hardware eventually asks for.