What speed to drive for turning around w/ a rider?

I know the shape to make the u-turn in (sort of going up and down the p) but how do you change your speed? I've never really had any complaints about my speed, and a lot of riders seem to enjoy going outside the turn to pick up the extra speed boost.

Usually i've tried to watch the rider and depending on where they are, keep it such that they're going about the same speed. So i slow down if they're on the outside and speed up if on the inside.

Thanks!