I have the Pentair 261152 MP Valve and I don't follow the 'turn only 1 direction' rule. I don't dispute it but I haven't seen any issues with not using that rule.
Regarding potential Gasket damage (assuming we're referring to the 'Spider' Gasket) if valve is turned in either direction, that shouldn't be an issue if the user is shutting off the pump & allowing a few seconds for the valve handle to relax (a slight upward motion after the water pressure is nulled). The handle should lift the Diffuser (sometimes referred to as the Diverter) assembly upward, not in contact with the Gasket so when the valve is rotated, the Gasket isn't in play regarding damage.
If the Valve Spring is defective, weak, or broken, that would affect the Gasket although it's most likely one would encounter other issues with that, ie, leakby into the Waste/Drain outlet, etc.
One thing I've wondered about regarding the 'one direction' approach, is that may reduce wear on the Diffuser Shaft O-rings & the Top Plate. For example, if debris is lodged in that area, multidirectional rotation could reduce the life of the shaft O-rings & the plate sealing surface.
The last time I rebuilt/lub'ed the MP Valve assembly was Dec 2015. The handle is beginning to show some resistance when rotating so I'll probably pull it soon for a re-lube. I might try the 'one-direction' rotating rule afterward to see if there's a notable difference in maintenance cycle time between re-lube's.
