[Nabeshin]

Hold on though, it's not HOW MANY REFUNDS, it's the percentage of refunds vs purchases that matter

Not true.

Amazon operates on a return/refund rate using an anti-fraud detection algorithm, and If you abuse their service with an Influx of returns, there's every chance the account In question will be flagged or closed - regardless of the amount of purchases made.

Well, my influx of returns never warranted an OFM mail so far, despite having up to 4 open returns at once (i let them build up so i could ship them all on a single trip to the post office, lazy me) that were also running kinda late, probably shipped on the last available day
So, at least from my experience, I'd recommend keeping a low refund:orders ratio before focusing on low refunds only, since even just 1 return out of 2 orders would be a 50% ratio which obviously isn't good