My experience in stake are really good for transaction side, more than around 10,000+$ are instantly for me. I don't know for other, can be have different situation since total deposit, waggering and rank could be taken as the aspect.
I have a little experience my biggest withdrawal is around $5000 of course it's instant with a low deposit and wager I got something big in the slot game
I assume if we get a big win in the Slot and Live game it will be in an instant process but if all wins are obtained from sports betting it will need checking and have an impact on the withdrawal process because we know that in sports betting some users can cheat the casino this is supported by almost all users who have problems with sports betting games because it can be manipulated. Besides that Stake also has a way to check our game statistics just try deposit $100 and wager $10 then ask for withdrawal I'm sure your withdrawal will be rejected because it has not met the requirements 1x wagering this means that every withdrawal will be through checking.