In the anapanasati there are 16 steps enumerated, but in practice we seldom count them out in our heads (once we understand them and have gain some proficiency with them, that is). Often times we develop two at a time, e.g., 1 and 2 together as we establish ourselves with the breath; 3 and 4 as we settle into the sense of body; 4 and 5 as we reap the result of being collected and relaxed.
What Than seems to be advocating is a method akin to anapanasati, where a desired result is achieved by steps: first, pick a spot and feel it, then second, spread out to the whole body; the final result should be a sense of being full bodied. By using this kind of sequential method we avoid the problem of missing some important detail which we could have used in mastering the 'full bodied' result.
The better question is whether your result differs significantly from that which he describes. If you accept the premise that he is teaching a method for jhana, then you can compare his descriptions with the jhana descriptions in the canon, and you can also compare your experience to the jhana description in the canon. This way you have two other reference points by which to compare your results.
From my own practice I've found that picking a point in the body where the sense of breathing is most pronounced is an important step to establishing the 'full bodied' result which I'm after. The goal for me is not to rigidly fix my attention to a small point, but to establish that initial perception of 'body' -- to turn my gaze steadily within. Once my gaze is steadily turned inward, I can cast it around the experience of body. As I do that, I quickly find that the experience of body is a pretty interesting, and that insterest cuts off the remaining distractions with 'out there'. Then I can calm this 'scattered' process and focus on the single sense of 'full bodiedness'.