A Lieberman wrote:

A person told me it is better to push the primer slowly rather
then quick shots.

The primers on the two aircraft I have owned both were slow to fill. If you
pulled the primer out rapidly, you wouldn't get much (if any) gas into the
primer. Once the primer is full, however, I don't think it makes any
difference whether you push it rapidly or slowly.

Is there a benefit to letting the engine run on one set of mags for a
period of time during the runup?

You should let it run on one for a few seconds (I count 4 when I do a runup).
This lets you make sure that the drop is not excessive. I switch back to
both for a few seconds before changing to the second mag.

George Patterson
The optimist feels that we live in the best of all possible worlds. The
pessimist is afraid that he's correct.
James Branch Cavel