When prices are falling down i always try to hodl. Before i invested money in crypto i told to myself that if something goes wrong i will be ready and will not panic. Situation can change very fast in crypto, so there is no need to make bad decisions.
I agree with that, if you bought something, then you have already analyzed the project and have trust in it. However, it is pretty important to analyze the whole portfolio frequently, if the projects are following the roadmap and the targets. If not, there's should be no doubt to sell it and purchase something else.