This advice seems to contradict what
I've read in other books. Most other's seem to recommend a varied
retrieve.

I have been fishing sliders since the early 80s when I read his book and it is
different. I never retrieve anything with a steady motion EXCEPT sliders, and
maybe drop shot, which is really fished still. I want the slider to look like
a minnow easing along, not necessarily a hurt baitfish struggling. In fact, I
catch most of my fish on sliders as it sinks on a tight line, with no retrieve
at all.
Ronnie

http://fishing.about.com