Idea:

This glyph, initiating Tuesday, is written exactly in the same way as those which initiate Thursday and Saturday. That surely is a sign for the reader to try to understand.

I guess that the straight horizontal short side at the top - which also Sunday has - is implying a higher status than the downward sloping corresponding sides in Monday, Wednesday and Friday.

At least that was the situation in the Roman circus (cfr Euripus in Hamlet's Mill), where the altars of Moon, Mercury and Venus were at a lower level than the rest of the altars.

... The Euripus, which has already come up in the Phaedo, was really a channel between Euboea and the mainland, in which the conflict of the tides reverses the current as much as seven times a day, with ensuing dangerous eddies - actually a case of standing waves rather than a true whirl. We meet the name again at a rather unexpected place, in the Roman circus or hippodrome, as we know from J. Laurentius Lydus (De Mensibus I.12), who states that the center of the circus was called Euripos; that in the middle of the stadium was a pyramid, belonging to the Sun; that by the Sun's pyramid were three altars, of Saturn, Jupiter, Mars, and below the pyramid, altars of Venus, Mercury, and the Moon, and that there were not more than seven circuits (kykloi) around the pyramid, because the planets were only seven. (See also F. M. Cornford's chapter on the origin of the Olympic games in J. Harrison's Themis (1962), p. 228; G. Higgins' Anacalypsis (1927), vol. 2., pp. 372ff.) This brings to mind (although not called Euripus, obviously, but 'the god's place of skulls') the Central American Ball Court which had a round hole in its center, termed by Tezozomoc 'the enigmatic significance of the ball court', and from this hole a lake spread out before Uitzilopochtli was born ...