I recently bought my first biscuit joiner, a used Porter-Cable. The
previous owner had apparently set the depth too shallow because when
dry-fitting boards the biscuits bottom out before the joint closes.

I increased the depth with the fine adjustment for my first test joint
so the joint closes when dry fitting. But when I added glue to the slots
I started to wonder if I ought to cut a little deeper yet to give more
space for the glue.

How can I set the depth to the ideal, or am I worrying about something
that's not critical?

Bill