Um... that's ridiculous. If after a flight, you notice a dead gnat stuck to the hub of your prop, are you going to ground the airplane and send it for prop balancing? Not likely. OTOH if you notice a dead raccoon impaled on one of the blade tips, you probably ought to get it checked out.
live in the real world will you!
if the prop in action isn't causing vibration then its balance is close enough.
yr right mentions a number of factors. like any engineering the answer is as good as the assumptions.
this was a question about maintaining a WOODEN propeller that has been in service on an aircraft.
the assumptions are that it is competently manufactured, i.e. both blades have the same pitch distribution, aerofoil distribution and blade area distribution.
that it has been properly set up on the aircraft and has now deteriorated.
I suppose that I should state the obvious. that the spinner is balanced.
that the spinner attach screws are symmetrically disposed about the backplate and are the same weight. the lockwire is close enough in balance that it isn't throwing the balance out. the propeller attach bolts are the same weight, i.e. the same length and that the number of belleville washers under each bolt is the same and that the crush plate is perfectly symmetrical and balanced.
if after all that your prop is still causing vibration then a dynamic propeller balance is the next option. Jimmy Williams in Albury does a good job of that.
mine, maintained as I have described, flies vibration free.
btw you guys in the SAAA should ask to see Shirley the redheads balancer.
I machined it for her.
resume own navigation.
your mileage may vary. :-)