Just a quick question. Do you also get instant withdraws when you win (and cash out) like 500 ETH or more?
The main limitation there is hot wallet size, big transactions like that can quickly reach the full amount of the available hot wallet (as the hot wallet size is limited for security reasons),
and thus be delayed simply by the fact there aren't enough funds in the automatic system to be processed, which then needs manual interference of someone moving funds to refill the hot wallets.
Determining the full hot wallet for most coins is hard, as all funds are spread over many different addresses, with ETH however, there is just one main address,
so we can plot the balance of that one to guesstimate the
"instantly available" funds.
Doing so from block 1,012,078 (Feb 2016) results in the following graph:
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.snag.gy%2FRgN76t.jpg&t=665&c=L463zocLg2zNlg)
As you can see, at one point, there were almost 10k ETH in the hot wallet (though that spike is just short, as the funds of course were quickly moved into a more secure storage location).
While that historic chart is nice to look at, it doesn't give us much information about the current situation (numbers from 2 years ago are kinda outdated, especially with all the price changes since).
So let's zoom in a little, and look at a graph for the last 4 months:
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.snag.gy%2FLelqCW.jpg&t=665&c=c6DM83vCdWOucg)
While the wallet balance fell below 100 ETH a few times, most of the time withdrawals of at least 200 ETH could be processed instantly from the available funds in the hot wallet,
with there being at least 500 ETH or at least 1000 ETH available a fair amount of time as well.
I have no way to know about Mayson's transactions, but I would guess the latest drop in hot funds from cca 450 to cca 50 comes from them withdrawing what they had won at one point.
Which also means their withdrawals have been processed instantly from the hot wallet, but that is (as already mentioned) just a guess.
This post focuses only on the wallet based answer to your question and ignores manual checks and any other reason for transaction delays.
It's not a complete answer and not the best one you can get, but I think it gives a fair estimate of what you were looking for.
Also charts, because nerd loves charts <3