Casino nowadays should really be having that standard instant withdrawal.If there are some hold ups and pendings then it would be varying into some
issues which is likely on this case.
Only few casinos have that feature of instant withdrawal and even at that it is not a guarantee for the transaction to be instant 100% all the time, since some time network congestion and other blockchain related delay may occur but at the most withdrawal shouldn't exceed few hours and if it go beyond 24 hours then it should be reported because some casino can deliberately delay withdraw processing due to their own internal errors.
*But most reputable casinos already have an established system that process transaction ASAP.
No, there are a lot of them actually. Instant withdrawals are one of the things that a gambler always requests so almost all casinos ensure that they have this. A delay, pending, and rejected payment can still happen though and that is to prevent an abuse. If there are newbies who came here to whine about this matter then we already know the reason why. But other than to prevent an abuse.
A problem in the blockchain can also be the reason like you said. I already tried playing on this casino here and so far I have no problems. My withdrawals went smoothly and fast even though my first winning only came from their faucet.