I am used to abseiling with a prusik cord, which gives me protection for the case I lose control of the descent speed.
However, I have heard that in canyoning, in some situations, using the prusik is considered undesirable. So people descend on ropes with just a braking device, and without a prusik.
Is it really the case? If yes, what makes it a valid technique specifically in canyoning, and not in e.g. rock climbing?