The performance of a watch in need of service can be improved by regulating, but it's a bit hit and miss. You'll never get a watch to run consistently if it's in need of service, but it depends how badly it's running too. A couple of mine need servicing, they're only used very occasionally so I`ve regulated them to give reasonable performance till I get around to working on them.
A Timegrapher's a really useful piece of kit, trying to regulate a watch without one is difficult to say the least.
Paul