Update reserve in advance #13
Description
Instead of waiting for our reserve to become invalid, we should start increasing it if we "get dangerously close to the limit".
As a consequence, we need a model to try to predict spikes as the moment where we get close to the limit is in practice not so long before we actually cross it. And having the user refill our reserves takes time.
Alternatively, we could allow some small and short spikes but increase if the tendency (eg comparison of the average of the fee paid during the last six months) goes up.