When I saw this thread last, I.thought it had pretty much run it's coarse with lumens and color. I spotted it again was curious how you spread the thread how this long.
Ah, a "new build"..... in need of a title change I think the chase light subject might hold wider appeal 
(?)....but congratulations none the less for designing more than one example of the way chase lights are done in games and carnival equipment. Minus spaghetti wiring, relay banks, or motorized contacts & armature plates of "old stuff" too.
A board mounted opto isolator would likely be used if the chip driving it was "special" in any way. Even Stans board with jumpers have some "factory made" twins out there.
One resistor was used, but 1 resistor at each set or each light was more common later because that way those circuits can fail and be diagnosed fast and individually, with less chance of effect on the other circuits and spreading the resistance's heat around too.
I.e. one light out at a time will be the "easy to see, common issue" with many resistor per led, but there a possiblity yours will drop one led, or loose everything (to the lone resistor) or at least sets (resistors for sets)
In a business application if the 100% failure can be avoided with complexity, complexity is usually chosen. A buisiness would rather have one light out and the others working vs a dead sign...always; so highly seperated circuits are more likely to get used than shared sets or singles.
There is nothing "wrong" with any appraoch here, I think you're taylored to your need pretty well too. An opto isolator would just be a bonus to protect the PS board and could maybe be done later as a plug in module.
Neet trains & it's pretty much done from what I see; but I saw a video of red chase lights on one too. Do you guys know, do they have red? Or was the video I saw "doctored" ?
