The README could have answered that for you.
100% chests is only on hard and tough difficulty.
Vanilla only had a 33% chance.
Same goes for traps.
Only on the opener. The collars on the other guys only count for money.
And if you wanted, you could only equip the collars after defeating the enemies, before opening the chests.
Really only if you want to deal with the menu 8 billion times.
But don't think about farming low level enemies for rare stuff, there's a nice penalty to the rare drop chance if you're too high compared to the victim.