Accuracy on the wrist Vs timegrapher

[Simeon]

I have a couple of different watches that probably need a service and when you test them on the timegrapher, they have pretty poor results across a number of positions. When you wear them, they seem to keep excellent time (certainly not losing any time in an obvious way across multiple days).

One example is a Vostok Amphibia with a 2409 movement (not the one I recently serviced ) that has rates that are generally negative in all positions, sometimes low (say -5 secs per day) and sometimes more (say -50 to -100 secs per day) in vertical positions.  It definitely needs a service. I have worn this for 3 days now and can't notice any loss of time (but then I am not synching it to an atomic clock and measuring it to the nearest second).

The actual rate of the watch is supposed to be an average of all the positions and other factors might be temperature and how much I practically shake the watch. What else could be the reason that a watch oerforms well despite having poor figures on a timegrapher? If I didn't have one, I would assume the movement was in good condition because of the accuracy it delivers. 

Gratuitous wrist shot of the watch in question. 

[Neverenoughwatches]

25 minutes ago, Simeon said:

I have a couple of different watches that probably need a service and when you test them on the timegrapher, they have pretty poor results across a number of positions. When you wear them, they seem to keep excellent time (certainly not losing any time in an obvious way across multiple days).

One example is a Vostok Amphibia with a 2409 movement (not the one I recently serviced ) that has rates that are generally negative in all positions, sometimes low (say -5 secs per day) and sometimes more (say -50 to -100 secs per day) in vertical positions.  It definitely needs a service. I have worn this for 3 days now and can't notice any loss of time (but then I am not synching it to an atomic clock and measuring it to the nearest second).

The actual rate of the watch is supposed to be an average of all the positions and other factors might be temperature and how much I practically shake the watch. What else could be the reason that a watch oerforms well despite having poor figures on a timegrapher? If I didn't have one, I would assume the movement was in good condition because of the accuracy it delivers. 

Gratuitous wrist shot of the watch in question. 

Pictures of the tg readings in different positions will help, also a few of the escapement and balance might shed some light on the matter