Getting back on topic:
There are always multiple choices when adding lights.
First, since MyDMX apparently has some new issues we need to address/resolve:
PLAN AHEAD. There is no valid reason to bunch fixtures right on top of each other with no space between them. In my case, I have my fixtures addressed to be compatible with my DMX Operator in the event I need to fail-over.
Logical assignment: While this one doesn't apply to me, SerraAva provides a great example of how he assigns lights. Go find it elsewhere ehre. While it doens't work for me, it may work for you, or at least a variant of it may work for you.
Duplicating addresses: No sense in burning addresses if you don't have to. If you don't need such control, double up, triple up, whatever.
Didn't leave space? Add to the end. Ain't that hard.
The thing I am getting at is that even though I am a sound guy and not a lighting guy, I have enough experience and knowledge to know how to use some vision and plan ahead. In my current MyDMX universe, I'm happy with how things are. When I get some LED wash bars, even though it may make more logical sense to stick them near the 64 LED pros, I'm going to throw them at the end of where I need to place things. If I add more 64 LED pros, I'll double up. If I add more wash bars, I may add on or double up on addresses.