High water mark, no profit no fee, Monthly or Bi weekly. Broker collects. That's a fair deal.
If the client declares a dispute and closes his account, contract or not, what chance does the MM have of collecting? Paypal won't even handle an money sent last week dispute, never mind a year old fee.
And if you use banks, and the fee is only a grand for the last 12 months for that client?
No ladies, it makes every sense to settle often, via a third party, from a financial point of view and from a fair point if view.