The timers adjust themselves automatically depending on the success, reaches but failed, and untouched ratios.
What you’re experiencing is the timers adjusting depending on this alone.
The timers adjust manually to take into account the variation and challenge of the landscapes. Hunting on a flat world will end up with shorter timers than on a island-lava world. But maybe the lava world is then easier??
The event is extremely sandboxy - IMO. Vary your tactics. Vary your location. Sometimes it’ll be hard, but sometimes it’ll be easy. Easy will then become hard. So try something different then. The event rewards adapting and of course speed.