I use one until it breaks, that way the back up is fresh and ready to go. I’ll use it here or there if there is a tape vs skate blade catastrophe, but typically stick to one. My nightmare would be using both equally, then having them both break or go soft at the same time, and not having a fallback option.
The answer there is to have another ”in case of emergency” back up that I don’t use, but that seems like too much*.
Over the past few years, I just recently entered the world of having my back up stick be a quality stick I liked. Historically, my back up was something that had gone slightly soft, or a stick I didn’t like much. But, in the rare cases I’d have to make full use of the back up stick, it was a clear step down and got in my head.
*realizing right now that I have multiple uncut, untaped to-be-used-later sticks downstairs. Ugh. hahaha Damn you internet/consumerism!!!!