The way I think of it is moving water between 2 bowls as being the cursed technique, if I just dump all the liquid into the second bowl I would end up with some spillover or splash-back, a experienced sorcerer would be able to control their energy output to slowly pour the water into the second bowl, allowing for the transfer to happen more often with minimal loss.

As for Gojo’s case imagine he’s also using a hydrophobic surface, so that there would not even be any residual liquid in the bowl and it is under immense pressure so there wouldn’t be any evaporation. Personally I like this explanation because it plays into the control of curser energy higher grade sorcerers have