If you want “high accuracy” with your mechanical calibre, it is certainly within your reach, regardless of who made your watch.
Every morning, I set my low-end mechanical watch according to the atomic clock on my bookshelf. As I wear the watch throughout the day, it is rotating through likely all six “positions” (face up, face down, crown up, crown right, crown left, crown down). Mechanical watches are optimized for exactly this scenario. By the end of my day, my watch will have gained about +1 second. This I think is more than adequate. And, to provide all available information, my current daily wear watch is using either an ETA or Sellita equivalent for the famous Valjoux 7750. Your watch movement is far
more carefully constructed than mine. If you leave any mechanical watch in one position only for a long time, it will not be as accurate as it would be if you are wearing it.
I suspect there is nothing mechanically wrong with your watch. In fact, it’s my opinion that your watch probably didn’t require a servicing either. Nevertheless, you did have it serviced, so I think if there were any mechanical defects (such as worn gears/levers or inadequate lubricant) those issues will have been properly resolved.
Since you seem to like mechanical movements, you might wish to consider investing in a watch timing device. At the moment, I have a very, very small watch collection. Your watch collection is likely larger than mine by a very big multiple. But since I very simply must have time accurate down to the second every day with every watch I wear, I bought a Weishi Timegrapher. They are very inexpensive, when compared to the cost of a decent mechanical watch. Therefore, I know down to one tenth of a second the average daily time drift of every watch I own in all six positions. But frankly it doesn’t matter all that much. The difference between minimum and maximum drift for my mechanical calibres might be a total of 6 seconds per day (-1/+5 or similar). But when I actually wear the watch, the timing accuracy is simply marvelous, no more than +1 as I progress through the day.
As I said, it’s my opinion that your watch might not have needed a service. What you may want to look into is whether your caliber can be regulated. Regulating a mechanical watch is not servicing the watch. It is adjusting specific parts of the movement so that the overall daily accuracy is improved. I think, perhaps, this might be the direction you might like to explore.
Keep in mind that a subset of mechanical movement owners who have a calibre with “hacking seconds” want the watch to run fast by a few seconds when the watch is in a preselected position (for me, it’s the face up position). This allows the wearer to hack the seconds into perfect accuracy each morning and have (typically) perfect timing accuracy for the day.
Normally I would not write a post on such an esoteric practice, but you seem to want very high accuracy from your mechanical watch, and in my opinion, you can have it.
I do this every day with my watches, and it works for me. Even with my current daily wearer being a Sellita/ETA, the accuracy is phenomenal.