Half your payees prefer PayPal or Venmo over bank transfers

A wallet payout is addressed to a person rather than to an account, and the identifier is usually a phone number or an email. That is a contact detail rather than a financial one, and the difference decides most of what follows. There is no account name to match against, so a mistyped digit reaches a real stranger instead of failing. There is no bank or branch code to validate, so a structure check tells you close to nothing. And the balance that lands is a claim on the wallet operator, so what the recipient can do with it next is set by that operator rather than by your payment.

A phone number can lawfully become somebody else. In the US, providers have had to age a number for at least 45 days after permanent disconnection before reassigning it since 27 July 2020, with residential numbers aged between 45 and 90 days and business numbers up to 365. The FCC has run a Reassigned Numbers Database for subscribers since 1 November 2021, which answers whether a given number was disconnected after a given date. So a payee record holding a number confirmed two years ago holds an identifier that may belong to a stranger now, and a payout to it succeeds, because from the operator side it reached the registered holder of that number.

Re-verifying an identifier before every run sounds like unacceptable friction, and for a payee paid monthly it is. Time since the last confirmation is the better trigger. A payee paid every month has confirmed the destination implicitly, in the sense that the money kept arriving and no complaint followed. A payee last paid fourteen months ago has confirmed nothing, and is also the likeliest to have changed number, changed wallet, or stopped using it. So the cheapest control is a re-confirmation prompted by the gap since the last successful payout, and the figure to decide is what that gap is.