But still...the enhancements are not unlimited.
When you have created all the superior potions, you have a lot of herbs around which are pratically useless.
True also of The Witcher (especially) and the Witcher 2. I had all the potions I needed, and more made, I had an inventory stuffed full with alchemy ingredients, and those I couldn't carry packed in huge quantities in my luggage at the inns. There wasn't any point in herb collecting for me at-all after the end of chapter 3 in The Witcher. Still did though because I could stuff a few dozen more of "that one" into the ingredient slot before it too was maxed out.
The same happened (more or less) after the end of Chapter 1 of Witcher 2... had all the potions I needed for the rest of the game and I only collected ingredients because they were there. (Crafting materials I was collecting and using throughout the game - but I had huge stocks of some materials in the luggage - there is also a little overlap between these).