Exactly. Depending on the team, I usually try to start off using something mostly by the book and we adjust from there. Some teams need more structure and some suffocate under it.

A business has to understand that the processes that are best for software delivery are orthogonal to the ones that are best for business.

Namely, (good/agile) software development demands fluctuation and iteration where business plans seem to thrive on long-term forecasts and projections. Waterfall would absolutely be the best things for businesses... if it worked.