Instead of boosting the stamina and power of the bosses Blizzard could keep the stamina static and only increase the bosses damage. This way they are still more dangerous, yet don’t slow down the run by such a drastic amount.
They could also make Tyrannical weeks have extended timers, which would most likely have to be tuned over the seasons.
I also like the idea of there just being some kind of extra mechanic on certain fights, but could also see the headache that would become.
Or delete it.