I certainly can't/won't dispute what
@bill_delong and
@WickedFog are saying. I believe there likely is a negative effect by running a matched set of batteries independent from one another.
I don't dive that deeply into it though. I buy the cheapest batteries that meet my needs. As such, I'm willing to roll the dice if you will.
What are the chances that the 2, 2s packs I bought from amazon are even matched to begin with? Yes, they are from the same manufacturer and of same "specs" but.. who really knows whether they "match"? My guess, they don't.
The idea that running a battery solo is going to change the batteries characteristics or specs enough to matter makes zero sense to me. Maybe it does, IDK..
I agree that every battery has a "limited number of cycles" and therefore looses a bit of life with every cycle.
I will continue to do what makes sense to me until I find a reason not to.
I'm just having fun on my backyard track. If I were into competitive racing, I would surely be more regimented with these things.