Operational RPM

Hello, I have a NHTZ22da that I now have about  used for 19hrs .  I am still getting used to the unit and really like it a LOT!.. I am struggling a little to find the sweetspot for RPM for general transport, mowing etc. There is this cool little indicator on the Tach that says '540' I assume that is for the rear pto but is that were I should also run the tractor for general use?  Sorrry if this should be intuitive.

The 540 on the tach is for optimal PTO speed.

For other tasks, use the RPM that "feels right".  There is no magic number.  In general, you'll probably find it's significantly less than the RPM's recommended for mowing.   You'll want to be in the ballpark RPM of where it's doing whatever the task at hand is without seriously bogging down.  It varies by task but in general, I'm running at about 1/2 of the PTO RPM.