It's a great exercise, I think. When we get it running in the testnet we will need a lot of people with different ways of interacting, and we will figure out what is typical and what is the range.
It isn't gonna be a hard, simple limitation, think of a fuel tank, that fills up to a certain amount, and when you use it, it depletes it. The tank can fill up to a certain amount, if you do nothing for a week, or so, and then it can't fill any further. It will take a little tuning to get it right, but once we know what is reasonable for humans, we can use this as a way to stop bots and spammers, because their behaviour is outside human parameters.
Bear in mind I'm a very casual Steemit user and I don't concern myself with what actually happens under the hood when I click stuff... Could Calibrae allow users to 'refill' their tank from their own spendable funds if they go through their share of the reward pool too fast? I know users can always send transactions but that's a clumsy interface compared to a simple upvote.