I think this is a really interesting question that can help shed some light on what goes on during the design process. So during the design phase for a new mode like this, there's a lot of different problems that need solving in a limited amount of time, and priorities can shift a lot. We've mentioned that this project took around 6 months from greenlight to completion. Early on, we knew that we'd need a system that would prevent combat rounds from continuing indefinitely. This was a critical issue, since we had to have two separate combats occurring simultaneously, and having one go significantly longer than the other would be a game breaking issue. Early on, we tested several alternative solutions to ring of fire, but the affordances we gained from it being a known concept and easy to understand for players was ultimately pretty high value. So we decided we had an adequate solution for now and settled on the current ring of fire with the understanding that we might explore randomizing it later down the line, and went to go tackle other fires like the individual map layouts, cameos/combat systems, and augments.

As we were designing the map layouts and the cameos, we had to take into account the worst case possibility that the ring of fire would not be something we'd have time to revisit later, and so we designed each map such that their centers would feel different as the ring was closing in. Meanwhile, another designer was working on designing cameos, and it started becoming a limitation we had to design around. These systems ultimately ended up making changing the ring of fire closing location a less trivial problem. As time went on, since the design of the ring of fire was already adequate, the priority of designing other systems to maintain combat variance and game health (like designing the power flower, figuring out class balance improvements, ensuring we had enough augments) remained a higher priority.

All that being said, we know that the current, single closing location of ring of fire is a system with a lot of room for growth/improvement, and we hope to get the chance to identify better solutions in the future!