Offshoreonly.com - Rolling engines over while winterized...Any benefit?

Your opinions on this appreciated,

I did this on my last Fountain (a 1998 29 single w/HP500 carb) and again on my 35 (HP500 carb)...every two or three weeks during the offseason when the boat is winterized, I put a 3/4" socket (w/pullbar) on the lower pulley, and rotate the engine either 1/4 or 3/4 of a turn. The though being that a least one intake and one exhaust valve are pretty much fully open and their valve spring is fully compressed. Probably a few other valves are partially opened or closed as well. By rotating the engine, it should prevent the same valve springs from being fully compressed for 4 or 5 months.

By rotating either 1/4 or 3/4 of a turn, that keeps the cam from being in the same position (I think the cam makes a half rev for every one rev of the crankshaft :confused: ).

This is just something I do out of being bored in the winter, but I wonder if it actually helps any. I've never had any valve spring issues, even on the 29 which was a pre-2000 HP500 carb motor which was susceptible to inner valve spring failure. I guess I also get piece of mind that the motor's are not locked up, although the boat is kept in a garage so it doesn't see too many days of freezing temperature.

Any thoughts.