@CornishBeard When I use just Jojoba or Argan my beard can still feel a little dry, when I use just Castor or Olive, it feels greasy. A mix gives you control over exactly how heavy you want your oil - and in turn your beard - to feel.

I have written a bit about different beard products here:
moustache cups and mugsbeard brushes and combs
beard literature | simple homemade beard oil

my beard journey | my bart * aber herzlich beard oil | Bartöl store (external link, not affiliated with or endorsed by beard board)