I doubt it will reduce SOW checks unless there is a holistic approach to each customer using a centralised system, which may be on the way anyway, or even if use already to a degree.
The clue is kind of in the description; Source of Wealth is to find out where the money came from under AML guidelines and the reason a casino is 'legally' obliged to ask for customer invoices etc.
Due to the nature of money laundering, they are obliged to trace to the original source, so if you are self-employed and your customer pays you 15k, and you gamble 15k, they need to know the legitimacy of those funds to combat laundering.
Affordability is purely about if you can afford to gamble and not really to do with AML. It's about if you can afford to deposit the money that you do. They should take withdrawals into it as well, but they won't, or don't, I don't think.
p.s. Just to add maybe a more direct answer to your question - I don't think so. You shouldn't really get a SOW check on a 50 depo (I don't think so anyway, seems a bit overkill) that leads to a huge withdrawal, but many casinos use the AML requirement to frustrate the customer.