From Diablo Wiki
added synergy entry
Potions are dropped based on the Act you are in, and difficulty level is not a factor. So you can get full purples in Normal/Act 5, but only partial purples in Hell/Act 1. No, it's not fair.
This is not a skill a [[Barbarian]] needs to use that often, if he has decent equipment and leech, but it can be nice to keep full of purples, and others in your party might appreciate it. One point is generally enough, especially if you have the normal Echoing weapons on your switch.