As for myself, many years at the bench have created some definite
physical problems, as this carpal tunnel surgery scar reminds me.
Plus, there are some back problems.
My suggestion is to at first do what is comfortable but be
disciplined in varying that position from time to time. The
repetitive actions, whether standing or sitting, seem to be the
cause of many physical problems. These pains come on after time,
little warning, just a tinge here and there. Each day without
variation seems to add to the problem.
I try to adhere(lol! not very well!) to the idea of raising the
chair an inch for a few days, lowering it an inch for a few days. I
try to vary sitting positions. For instance, sitting on one leg
under the other, legs crossed, etc., can easily put undo and
unbalanced pressure on the back and shoulders. I sit to do fine
control work and stand to buff and polish. This at least does
provide a little variation through the day.
I see little I can easily do to change the hand positions in various
jewelry jobs, such as stone setting. These are the positions I need
for control and vary little. After a few hours of bead setting, for
instance, I might have to open cramped fingers with the other hand.
The GRS bench mate is a good tool freeing both hands to a wonderful
extent. This might seem pricy but if you can use such a device to
free one hand, half or more of the hand problem is redirected.
These devices were not around when I started. I wish I had learned
more of ergonomics then and given it more thought.
If really serious about the work and planning to be involved for
many hours and years, investment of what might seem too much money
today should pay for itself in years to come. When those years do
come, prevention is too, too late for problems that already have
been created. I see the simple plan of changing positions, if only
slightly may help a bunch.