Few outboards can troll at 1 mph. Many years ago the old Fishing Facts magazine recommended what they called back trolling. Trolling in reverse slows the boat way down. Problem is, unless you have tiller steer, turning the boat to stay with a contour becomes a problem. Of course, in those days trolling motors were more positioning motors. Today's generation can practically tow skiers.
I think the key is that modern trolling motors do not spook the walleye, even in 8-10' of water.