Post Shave Minefield

Alum - rinse off. Witch Hazel - leave on.

I found, when once I forgot to rinse off the alum, that it caused irritation quite shortly after drying out.
 
I tend to rinse them off, personally. They often make my skin feel pretty dry and lousy. Nowadays, and especially since switching to cold-water shaves, I've not really needed them. Not spilling very much claret if any these days!

As for the witch hazel, sometimes leave it on sometimes wash it off depending on how much I 'need' it. Again, don't use it much these days but it does a good enough job both left and rinsed.
 
I use a tiny drop of almond oil after the last pass while the face is still wet then a good rinse off with cold water. Pat dry the face and apply whatever alcohol based aftershave.

I find that the almond oil replaces what the blade took away and the AS seals it all in leaving the skin refreshed toned and smelling nice.

I drink a lot of water through the day so balms would leave my skin all greasy and I would have to wash my face a few hours after application.