A Stoic would say that negative emotions have root causes in the misconceptions you hold about how the world works, and what you can and cannot affect about it. If you don't proactively address those root causes (which doesn't require "expressing" the emotion, but does require noticing and judging it without reflexive acceptance) the negativity will in fact "keep flowing" and your short-term disregard of it will be less and less effective.

It's not a good "habit" to disregard negative emotions without also examining them.