There are a lot of project principles, and processes built on those principles, we think of as immutable: stationary--and proven--with time, experience, context.
Somewhat like the speed of light: Every observer or practitioner in any frame would see them the same way
Not so fast!
Sacred indeed! To be respected? Yes! Defaults that are best practice? Absolutely
But immutable? No.
Unlike the speed of light, Planck's constant, the G-gravitational constant, and a few others, everything else is subject to interpretation, framing, circumstances and context, and the advance of process improvement.
To be immutable in the project context is to be on the edge of denying "new physics" that might move the PMO to a more effective plane
New under the Sun
Just during my professional PM time, I've witnessed:
- Theory of Constraints
- TQM in multiple forms, largely abandoned
- Critical chains
- Agile methods
- Monte Carlo simulations into the main stream
- PERT dismissed
- Iron triangles, parallelograms, and other interdependencies
- Black Swans and other physics of the unknown (chaos, fragile systems etc)
- Risk matrix
- Etc
Buy them at any online book retailer!