It is very important to upload the new episodes on time. If you have a short delay not need to worry but if you are late by more than 1 or 2 days then its probably better to send a repeat show.
Many radios try to broadcast shows as soon they are released. So for example if you set up the delivery of your show to Monday, then its more than likely many radios will broadcast it on Monday evening or Tuesday because the exclusivity of the content. If you late with your show then they have nothing to play.
If you regularly have delay with your new episodes more than likely radios will drop the show.