Well I've just had a long and frustrating time doing my brakes. I've had the calipers off for cleaning and service, so the whole system had been completely drained. I followed the procedure faithfully, and my first comment was the PCV bleed was very slow. I had the vacuum pressure cranked up to about 15 inHg, the fluid started to appear quite quickly but once I had a solid line of fluid everything slowed to a snail's pace. I intended to flush at least a full reservoir at each step, but the PCV would have taken hours, and hours... However, my main problem was with the front brake. After 3 long bleeding sessions, sucking through 3-4 pints of fluid with no air appearing past the nipple, the front brake was still very spongy. Clearly I needed to do something to make the air, wherever it was hiding to bleed through. On my 4th attempt I unbolted the front left caliper, and with vacuum applied I rotated the whole caliper as far as I could in all directions (carefully due to the 3 brake lines attached) and SUCCESS, a large bubble appeared. I excitedly closed the nipple, popped the caliper back on the disc and to my great relief the lever now feels normal!!! I then did the same with the RHS caliper for good measure, but as expected I got no further bubbles.
So, my experience is that air can persist somewhere in the LHS caliper, and normal vacuum bleeding with the caliper bolted in position does not move it. I hope this help somebody sometime