Zone 5a gurus

Soooo. After a couple years of doing the same old I made this year a learning year. Planting earlier, planting later, growing up instead of out. Planting for seeds for next year and doing more reading.

I knew of this but did not really give it much thought until I read a couple interesting articles on companion planting. My question to you 5a gurus is do you  plant garlic in specific square in the fall because you plan to plant "x" plant next to it in the spring? I am building a new box this year specifically for garlic onion and tomato but should I be spreading the garlic love around to the other squares if the vegetables match. This would really mean planning next year's garden in October. 

My other big reading was 3 sister planting. Granted in my situation I think only 2 sisters is sustainable. With maybe the 3rd if she is short. Anyone else do that without using a whole box up?

Paul