Quick list of things to consider using the percentage system of
payment. Not all apply to all situations.
This is basically carrot and stick thinking so you'd better have
enough work to keep them busy.
You should, in the best possible situation, have someone who is not
on the % system doing quality checks. Percentage pay can lead to
sloppy work as speed becomes of more interest than quality. You need
to help your staff find and maintain the balance.
The above can also lead to hard feelings in the studio if the guy
who's doing the most careful work is consequently penalized in pay
because he's not clocking out as much numerically.
You can also suddenly find that your staff is reluctant to do
courtesy work. No percentage.
I worked for a large family business for ten years and they tried
everything during my tenure. What seemed to work best was a
competent staff, adequately paid, with a supervisor who's job
depended on timely and properly done work.