If you feel more comfortable spinning CCW, and you already reach about 350rpm that way (which is usually enough to get a 300 in most spinners, with some exceptions), you can just do that. Getting the bonus score from over-spinning only tends to help while trying to get into the score leaderboards of easy maps. Not straining yourself while spinning makes spinners act as breaks while playing a map, which can be useful to maintain stamina during the play.
If you want to optimize your spinning speed, try each direction for a while and test what works best for you. It is likely that, in the end, the fastest way to spin for you is also the most comfortable way to spin.