I've used a castor oil pack dozens of times, and pretty much as spelled out
by Cayce and presented in the book The Oil That Heals by McGarey. I find
no supportive material in what you presented from the School of Natural Healing
book. Supportive in the area of why the difference? Or, what
benefits are produced over the Cayce methods?
I've also done some small castor oil packs on the calves of my legs with no
heat applied at all. I've been incredibly amazed that just a small 6"
by 4" pack applied to the leg with no heat can easily produce the same
results as my "normal" pack of about 12" x 18" that I apply
to my abdomen - with heat. When I say same results, I mean full body
release of tiredness and even distressing emotions. I personally believe
that the important element is to get a saturated flannel applied to your body no
matter where you place it. Even though I've had success with the small
packs on the legs, for general use I still use the large pack on the
abdomen. (I keep my oiled flannel in a sealed plastic bag in the frige
between uses. Keeping it cold prevents it from going rancid and I
generally use the same one over and over for 8 to 10 months.)