Much like the pack that can be bought for the guild events, that gives a little discount. The pack gives unlimited of torches in the event. Can cost around 1200 gems.
This means people can do all Underspire rooms and finish it off whenever they like to.
Such a great request that I hope will come true.
You have to spend 300 gems per day, which is 2,100 gems minimum per week. A realistic price for unlimited Underspire moves would have to be higher than that - closer to 3,000 gems.
In my experience, I usually have only 1–2 Underspires YEARLY where I can’t clear all rooms using just the weekly torches. Most of the time I need around 4–5 x3 torch packs, and on the remaining days either zero or at most 1–2 packs. Overall, your option would result in an even higher gem loss.