Now and then I'll practice very high cadence, say 120 RPM or more and begin to bounce in the saddle. This indicates that the peddle stroke is not as smooth as it could be. On the hill, a lack of smoothness is wasted energy. So for me, climbing tactics primarily involves working on being as smooth as possible.
But as you say, when current technique or level of fitness is about exhausted, I revert to the tactic of "The Little Engine That Could". I think I can. I think I can. I Think I Can, and so on and so forth. AKA get stubborn.