User blog:Tekashto/Hidden Schedules

Aside from a few exceptions (e.g. Holidays), the updates in BCEN are usually delayed from the BCJP updates by 21 days. I've been wondering if certain stages (Merciless XP) follow a pattern as well, as they seem pretty much random. This will serve as a catalog, but help would be appreciated.

Stages of Interest
Tempered In Flame: 7/4/18, 7/23/18

Merciless XP: 7/4/18, 7/23/18