Herbalist-Related Questions

It's not half the recipes. You will forget 2-4 recipes each time you replace your herbalist; it's not proportional to how many you know at the time or replacement.

Do we know the exact amount of time it takes to research and create medicines? Is it different for different cures/balms/salves?

@BirdstarOfSkyclan, I believe the amount of time it takes goes down as the proficiency of the herbalist goes up. 

My herbalist has been on 99% proficiency the whole day. Is it because he's 6 years? Does age affect proficiency?

@Ohemaa

As far as I know, no, age does not affect prof. Must be very bad luck you are having! Just keep sending him doing his task, and eventually he'll earn it back.