For example, all of the elements might be landscape, all might be portrait, or there may be a mixture in the overall wall. Worst case (if the designers had complete reign!), there could also be mixtures of elements with different resolutions (1366 x 768 vs. 1980 x 1080) or even different aspect ratios (much less likely if the system designers get a say!).

If we were to drop the 1 in the 1H2T1H term, it would effectively be mixing the short and long definitions in the same row term. I agree that it would be easier to read and interpret from a human point of view, but it would make machine-readable parsing more difficult (although obviously not impossible), and in the interests of simple structure and conformity, we decided that it was best not to mix the two within an individual row term.