I carry a good whack of tips in the Fall--all Rio Density Compensated 15' tips--to make sure I am able to fine tune my setup to changing conditions.
In the cold water of the Fall, I like to get down a bit but not so far as to run a fly at the precise depth of holding fish. If I start ticking bottom with a fly, I change to a lighter tip.
Two years ago on a Fall trip, I saw others foul-hook a tremendous number of fish. The water was low and to a man, they all had Type V and Type VI integrated 15'-24' sinktips.
It got real ugly.