In addition, do not forget about the execution time - usually casinos require several confirmations, and I think that in modern conditions it is irrelevant to wait for a transaction to be completed for almost an hour.
Afaik most casinos only require one confirmation on bitcoin deposits and sometimes there are other casinos that require a few more for withdrawal requests.
I rarely play with altcoins but I think they're the ones that require several confirmations since the block times are much faster.
IIRC, there are even some casinos that do not even require a confirmation on deposit, they'll just credit right away once it's already in the blockchain, but during withdrawal, it should be confirmed before they'll process it. It usually requires 3 confirmations for bitcoin and it's alright because they have a good feature which credits your deposit without confirmation. However, I think there are only a few sites that do it now because it's a bit risky on their site, maybe 1 confirmation is a bit safer.