Power of the Rainbow vs. the Pits

[Chibi Rachy]

So, one of the simple rules learned in the very first episode and carried on out is that the Color Belt's powers are not supposed to work within the Pits. And for the most part, that occurs. However, there are some episodes where it gets stretched or ignored. I'm gonna provide some of the episodes that I remember where such a rule is easily broken:

Mom: Rainbow, Starlite, Twink, and Murky's mom are able to ride the rainbow directly to Murky's front door, with no problems whatsoever. The rainbow neither falters, nor are extra star sprinkles added.

Monstromurk: When Rainbow escapes from the rapids, the rainbow works very weakly, and is barely able to hold her. It also can only Romeo a short time later.

These are only two episodes I can think of off the top of my head, but I'm sure there are more as well. I can think of good reasoning for the bits in the Monstromurk that would make sense, but I want to hear what others think before I add my two cents to everything.

Discuss: The Color Belt should never work in the Pits, or are there reasonable exceptions to this rule? If there are exceptions, why did Rainbow never use them to her advantage all the time?