I still own an English verge fusee watch dating to 1815. After service by a watchmaker specialized in vintage timepieces it runs down it's full chain in 31 hours and loses one to two minutes when it lays face up on my desk. It is adjusted to 4 positions. When worn it can either gain a little or lose a little, but not more than ten minutes per 24 hours. Sometimes it just stops when carried around. But I don't use it. I just love to wind it up every once in a while and stare at it. Many people say this is beyond expectation for a verge fusee that old, but my watchmaker says, that even cheaper watches made about 1800 were designed to be within this window when new. When properly repaired and serviced it should be back to it's designed accuracy. Everything less is either caused by money saving repair techniques, a fault that has not been found and thus kept un-repaired or a built in fault which has never been corrected (his words).
My younger watches were from the 1940s to 1960s (all sold now). They were wrist watches and kept the time within one minute, gaining or loosing not more than 30 seconds per 24 hours. Depending on the build, I tried to wind them every morning at closely the same time for the period of wearing them. On some watches I noticed that they lost a few seconds during the first half of the spring and gained about the same amount of time towards the end of the reserve.
To find out if their accuracy was acceptable, I always compared these watches with my mobile phone's watch exactly 24 hours after I fully wound them. I found anything within 30 seconds acceptable. One minute loss or gain was way too much for me. But this refers to less than higher end watch movements.
A vintage chronometer which is repaired, serviced and properly maintained should be withing five seconds per 24 hours. But I never had one. All watches I had in daily use were properly serviced and maintained on a regular and frequent basis, say every four years.
I'd say, it has to be serviced/repaired...
Chances are, that it has to be cleaned and oiled. If not cleaned, it will wear and things get worse, likely making a repair necessary, translating to higher costs. Cleaning and oiling is a standard service which is usually not expensive if not cheap. This extends the lifespan of any mechanical watch.