Flying is a dynamic situation which is exactly why we use throttle/pitch curves. You want to maintain a constant head speed and this can be checked on the ground with an optical tach, which costs under 100 dollars. Some people with a bit of experiance can do it by ear as well. You need another person on the ground to do the rpm measurements because its hard to look through the little sight on the tach, twiddle with the buttons to find your rpm and fly all at the same time.

Here's some facts. Your maximum pitch will be whatever your engine can pull, to maintain a constant RPM without bogging. Your minium pitch will depend on your skill level. As your skill level increases you will want more negative pitch up to the point it matches your top pitch. This will do 2 things. 1 it will make the machine more aerobatic. 2 it will make the collective stick more sensitve. If you think about this it will make sense.