Great post on a great topic. I feel like I'm pretty generous, I pretty much try to upvote everyone who comments on my posts at least a little bit, the more thoughtful the comment and/or if I have a relationship with.
I tend to give pretty good upvotes either 100% or 50% normally 20% about min, and even to half ass comments or bot comments normally 1%. I honestly feel like for the most part with the exception of a few people it doesn't really come back to me, people don't really return the favor. I'd be curious to see if I give less but spread it out to more people if that has a better effect.