We have a bathroom faucet (a couple years old), and the hot water side began to drip from the faucet (i.e. it was as though we were unable to shut off the faucet completely). Until I had a chance to replace the cartridge, I turned off the valve for the hot water under the sink. The valves look mildly corroded (photo below), and when I turned it off it did feel slightly stuck at first to start turning it, but after that point it turned fine, and it shut off with no problem.
Now, before repairing the faucet and ultimately turning the valve back on, the question has come up of whether turning it back on could end up being a problem, out of concern for us doing a non-emergency repair possibly then necessitating an emergency plumber visit: That is, since it is corroded, might turning the valve back on, or on and off at different points in the repair job, cause the valve itself to leak? How concerned should we be of a risk for such a leak in this sort of situation? And would the concern be for a large leak or a small one and only if it’s in the on or off position or always?