Regardless how much stamina you actually get, sip of water always burns the 20 energy (base cost, reduced by water quality.) This means drinking at 91% or above stamina, you waste energy.
This results in constant waste of energy if you use the default auto-drink. In PvP chase meta, this makes custom auto-drink that stops at 91% or more mandatory for high-level play.
To be clear, if you take a sip at 99% stamina, currently you spend base 20 energy to restore single point of stamina. If this suggestion would be implemented, you would only spend 2.
I now realize people would still use custom drink scripts to save up water to get every little bit of advantage they can (albeit getting more water while fleeing is easier than getting more energy.)
Still, I think this would be a big general improvement.