how much of what is tracked does not get used in a mix?
It's hard to say. R Kelly would only send exactly what he wanted in the mix. Basically asking me to put my sound on it with a little fairy dust. Then there are some producers who like and want me to 'weed thru' their idea's to come up with something appropriate to the market we're targeting. Some producers hear what I do and get inspired to add more as I'm mixing as well.