The CS told me it's policy that they fill "full-pay"* orders first; let's assume CS is right.
If this assumption is true, then the policy is about nothing but how fast SS can get a customers cash into their bank account.
If SS converts "full-pay" orders into cash by shipping those first, instead of taking the final flex-pay payment and shipping those, that's a win for them.
"Full-Pay" buyers have only paid (to date) a 10% NRD, so SS gets an influx of cash via the outstanding 90% of the total amount on each item they ship.
This seems unfair, as flex-payers have already fronted them 75%(ish) of the total.
But from their POV, why hurry to fulfill a flex-pay order when you've already gotten 75% of the customer's payment? All SS gets out of that in liquidity is 25%.
By this logic, it works against a buyer to pay SS a larger amount of money in advance via flex-pay for a pre-order than it does to keep your cash on hand, and pay them all at once. If you flex-pay they have access to your cash for a longer period of time (and you don't, which is a lose for you) plus they ship your order later.
This is bad policy that will ultimately backfire, especially as shipping schedules continue to wildly fluctuate and prices wildly escalate.
Powerfully lame.
* obviously this is not "full-pay" as they put down 10% when they placed the order, but go with it as that's how CS referred to those buyers to me.