Taxi at walking speed is what I used to teach in piston singles to new students who were still trying to turn on the ground with the yoke, were not used to brake asymmetry, and had never had wings and wingtips to worry about. I agree, it may be a bit over the top when you have to taxi 10,000 feet for takeoff, five times a day, and on a schedule in a jet. More than 5 knots but less than V1 sounds like a good rule of thumb!
