Good question! You can transfer data at the maximum speed for all your Epic apps, until you reach 20 GB. After that, your Internet speed for these apps will be lowered, i.e. to 512 Kbps. But don't worry, this is still high enough to continue using your apps. To give you an idea: in theory, you can listen to Spotify in normal quality at 96 Kbps. And did you know that you could listen to Spotify for over 480 before your 20 GB would have been used up?