That is why you mashout, or at least raise the temperature of the sparge water. Raising the temperature of the grain bed to ~170°F makes it less viscous (more fluid).
See if John Palmer's explanation makes more sense:
http://www.howtobrew.com/section3/chapter17.html
That's not what you said at all. You said to raise for a second infusion, which I didn't understand to be a mashout. If you're talking about a mashout, I'd agree although for a batch sparge it doesn't really help.