If the level is a mirror level you know that they’ll be a crystal chest room on each side. You get one crystal key but 4x chests initially to choose from. Once you open one you know that there will be a mimic on the other side now, so 2x the crystal chest reward assuming you kill it in time, one from the key and one from the mimic. The point is that it’s a rare level spawn but you know you potentially get 2x the crystal chest rewards. As for the boring exploration, it’s not like the levels are big is it.
If the level is a mirror level you know that they’ll be a crystal chest room on each side. You get one crystal key but 4x chests initially to choose from. Once you open one you know that there will be a mimic on the other side now, so 2x the crystal chest reward assuming you kill it in time, one from the key and one from the mimic. The point is that it’s a rare level spawn but you know you potentially get 2x the crystal chest rewards. As for the boring exploration, it’s not like the levels are big is it.