A flat bottom boat will slide side to side easier than one with more of an arc in it's bottom cross section regardless of the rocker.  Maybe that's what's happening??
Plus ST uses a kayak paddle so he's limiting the need to switch sides for course corrections.
Maybe you should try a kayak paddle first??
Or work on your J stroke with a straight blade?
A good J stroke won't slow you down like a rudder does, and can be very enjoyable.

I read ST's Redrock link and it's probably right about using a J stroke sitting in the center. If you've in a flat bottom boat it'll side slip more than turn. But I know from experience that it works fine in a boat with a more rounded hull, i.e. Argosy, Voyager, Racing C-1. But SR are usually more flat bottom so the J may not be the answer.