Yes, do not leave a tightly gagged person. You may take tightly to mean that they can not spit out the gag in an emergency. An emergency may consist of panic, choking, or trouble breathing. This is why we do not leave our subs/slaves alone in this condition.
The tighter the ropes the shorter the bondage. I check my slave for numbness or color change at all times when I have her bound.
A hard paddeling will leave marks and bruises. A whip or a bullwhip will leave deep marks and bruises. It may even break the skin if not used properly. This is where a little aftercare is called for.

Play safe!