It is difficult to say. A few days ago, there were congestions.
Lots of users have been having withdrawal issues on Polo (though not necessarily for ETC), and support tickets are backed up for a month. That is why I got off of polo.
Probably because they don't have 2fa set properly or they are withdrawing to a HD wallet like Jaxx and using the same withdraw address when they should be changing it accordingly after every transaction.