Deliberately making deposits/transactions under threshold limits to dodge mandated reports is already illegal. It's called structuring.
oh, good grief Joe-6! ya just had to go & ruin it for me didn’t cha? LOL
From that link, structuring applies to banks and CTR. It’s when depositing large sums o’money.
If my money is already in the bank and I decide to pay someone with three checks, I don’t see how that can be illegal.