Hello. Does anyone know if using an automatic watch winder can help improve the time-keeping accuracy of a manual watch? Specifically, an 1861 Speedmaster? My idea would be to manually wind the watch every morning at the same time and place it on a watch winder if I am not using it.

 

An auto watch winder serves no purpose for a manual wind watch other than if you want to watch it roll around and spin. It won’t wind the watch so it’s senseless...

 

That just made me smile

 

It would make your Speedy feel like it's training to go to the moon!

 

I think OP specifically wants to know if the spinning would even out any positional variation in timekeeping.

It's an interesting question and I'm not sure.

 

There is actually a difference on how the watch is placed when not in use. Both of my Speedy’s (sold to buy the 50th) has been regulated during the night by placing them in a certain way. They was both a little fast during use but then it got slow when placed on a table with the crown upwards, so after 24 hours it was +-1 sek.
The Earth’s g-force is always putting pressure to different parts of the movement, but it’s different from timepiece to timepiece (even the same movement). Only way to find out if a winder will affect your watch is to try it out and measure the difference.
This is why I love mechanical wathes... They are all different and feels alive!

Greetings from Norway.