Practice on grass
I agree with the previous post, it does mess with the timing, but the muscle memory is important and that does get better with practice, even just going through the motions with a pencil in hand while sitting in your easy chair.
I've found that when you get the river, doing about 50 switch casts to settle down and re-acquaint yourself with the current pull and wind will ease you back into the right timing. Then start with your best casts and work up the harder ones. So for me, it is switch, snap-t, strong side single and then the double.