I guess a different way might be whenever you change a property, it only changes it in that specific instance within that specific diagram that you're editing (at the top level, i.e. the diagram that's selected in the left-hand panel).

So if you wanted to change the photon from a circle to a star everywhere, you edit the photon diagram. But if you want to change the photon to a star just in one place, you can edit it in that one place and it won't affect the photons anywhere else in the system.

An advantage of this is you don't need to "hoist" a property from the Inspector into the Variables panel every time you want to change a tiny thing in a sub-diagram. A disadvantage is that it might be confusing if something deep is changed and it's confusing why this one Light Clock is acting differently than all the other Light Clocks. But then I guess you could click on the misbehaving Light Clock and find the deep thing that is changed.

Am I overthinking this? Any references about these issues? Vaguely reminds me of Jonathan Edwards' calling by copying idea from the first subtext.