I have a Watts single handle washing machine valve that was installed
by a plumber less than 5 1/2 years ago, and I only did the laundry
once a week or sometimes not for 2 or 3 weeks. Tonight it developed
a leak when doing the laundry. The leak was at the stem (handle). I
went to Home Depot and bought a new Watts valve for $29 and just
replaced the whole thing (including the O rings) except that I reused
the old elbow attachments since those were soldered on.

The new valve appears to work fine, so far, and I am keeping fingers
crossed that it stays leak-free.

My question is this: When doing the laundry I would typically leave
the valve half-way (or less) between Off and On rather than all the
way On. When not doing the laundry the valve was off. Do you think
the new valve would be less likely to develop a leak if I turn it all
the way On rather than half-way-on (or less) on when doing the
laundry?

(I now have a pressure-reducing valve where the water comes into the
house, so maybe I don't need to bother with the midway position as a
means of reducing the water flow)

Thanks,

Jay