Since it was such a large amount, FJ had to approve it
[...]
Just thought I'd ask if anyone else has ever experienced, and if it's a common practice for every online casino to do.
Unfortunately, lots of places do it because they know that if you can't withdraw you will probably be tempted to play some more, but it is borderline scammy behavior. Any reputable casino should allow you to withdraw your winnings whenever you want them.
Obviously nobody is going to keep their whole bankroll online, available for instant withdrawal, but there's no reason not to keep enough available online to service reasonable withdrawals.
At Just-Dice for instance we have a bankroll worth around $1.5M but only have coins worth something like $40k available for instant withdrawal. If you win more than $40k's worth you'll need to wait for up to 12 hours for the hot wallet to be refilled.
That is very true. Some times people after waiting for couple of days they will think just continue gambling instead of giving free coins to site.
12 hours to one or two days should be a reasonable time to check there system but they are asking for 10 business days minimum means they don't have confidence on there won system so they may need so much time. Something is not correct here.