Wonderful description. I teach the GT as ripples going out from the significator and, to a lesser extent, from topic/focus cards. Whenever I read a shorter layout (3, 5, 9 cards, etc.) I'm very aware that I've just selected a cross-section from the greater whole of all 36 cards, and that I may not be getting the whole picture. So, I'll often lay out a whole GT with the intention of only reading the two cards on either side of the significator/topic card, or may intend to read the square around them. I'll ignore the other cards unless I find I need more information or clarification regarding a certain card - and then the other cards are available. It's also helpful to see where the topic of concern lies in relation to the significator: is it near or far; what lies between; are they connected by a line, diagonal, houses, or mutual knighting to a third card? In a 15-minute reading I feel fine ignoring the other cards altogether - afterall, that's what I do whenever I lay out a short reading.