I guess that would depend on the size of the bank, and the bank's requirements.
In a small ($200MM) bank, we had statements dropped to Audit's attention monthly. Each month, we selected 2 letters of the alphabet, and scanned for large, frequent and multiple deposits.
Of all the statements reviewed there was only one question of frequent & multiple deposits - a loan payment clerk's husband owned a food cart and there were almost 50 small cash deposits during the month.
I believe many larger banks have programmed selection routines and review on-line.
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Integrity. With it, nothing else matters. Without it, nothing else matters.