I agree with the earlier insightful comments. I'd like to add that, in addition to my experience as a practitioner, in receiving I've found that, based on the practitioner's experience and training level, a more mechanical approach (on the way to increasingly subtle palpation skills) performed at the head alone can sometimes bring on a headache in the receiver. The practitioner's ability to call hydration to areas of movement reduces this risk, as well as venous sinus training.