On why only some icons would have them
I took the ConstraintLength icon . That is the established icon for length. I made it horizontal to distinguish it from // , the fundamental aim, and to make a visual link to the form of = , ie now it reads: length+equal in the establish metaphor.
Could you at least try it out and share the results?
Your idea, you do your own leg work
I'm not hear to crank the handle.
Since | means vertical, || would suggest some link to that. Note the UI uses the 45 arrow to distinguish "any length" from a vertical or horizontal length. Thus my new // says: not horiz, not vert, not equal; but parallel.
And lets see after, if any of the proposed solution can resolve the initial issue, by not leaving any loose ends
I think this does address the the issue I raised and I do not perceive any loose ends, If you do please point them out.
If there is agreement to adopt this improvement, I will tweak the // to have slightly more difference in length and try to get = a little larger.