its not really a stupid question. yes its true that sup will be better than junior and waaaaaaaaaay better than primary. but when you compound an item with a lower ranked base than the secondary or tertiary mat it's always best to use primary since it recognizes no ranks. and maybe a book to give it a push.

but yea best to find or invent a recipe with a higher base and use sup for a less chance at failing or try your luck.