I never change the mast location based on the conditions, but the ideal position is definitely different for pretty much every foil setup I am using. You may not feel the need to move the mast if riding strapless, but with foot straps it's easy to feel the need to make changes.
For the setups I am using the mast location moves up to 5 cm. Basically every little change you do with the foil (change of the stabiliser, adding/removing a shim, changing the length of the fuselage, etc.) may require the change of the mast location for the whole setup to feel ideal.