About the only comment I'd make here.....as it applies to efficiency.....(and I'm no master of it so do as I say, not as I do).......be careful what you decide to do when you do it. Try to memorize how long you can hold one or the other and realize that the safest bailout is sitting.

I often muster the fortitude to stand for a climb, start to choke halfway up and realize I want to be back in the saddle but I know I'm gonna screw myself when I lose momentum by sitting & downshifting....(as quickly as I can and I believe I'm quick on the brifters).....and I'll have to regain that momentum, no matter how little and on top of the physical loss in efficiency, it also pisses me off and gets in my head.

Therapy much? LOL