Most of the value in pumped hydro storage, as for chemical batteries, is in load-shifting, particularly from daily collection to evening load. You use it every day, so opex should be minimal.

For tertiary, occasional use, efficiency doesn't matter much, and other considerations dominate. Gas and steam turbines need expensive periodic maintenance after operating for some period, so you avoid running them too much. Fuel costs money, too. (Unless you synthesized it yourself; but what you burn you cannot sell.)

Transmission lines complicate choices further, in large part because they go both ways, and must be scheduled to maximize usage because they cost a lot to build. The power they carry might be free at the source.