What parts of the PM Plan documents do you think are critical

Question

Out of all the PM Plans and project documents discussed in the PMBOK, what are the ones you would say are absolutely critical to project success within a technical research environment, and why?

Answer 1

The Risk Management Plan is the only document that matters. Every other plan, even the creation of a PMO or and/the naming of a project manager, is driven by the need to manage project risks and enhance opportunities.
The Risk Register should identify the need for any and all other project plans as risk-mitigating measures.

It really depends on the context of your project and the level of formality/standards enforced on the project teams.

All components are of importance, but how heavy/light/standalone they are will vary based on the nature of your project.

The only exception is the procurement related ones if there is no procurement involved in the project.