Good Practice, Not Necessarily Best
I do, of course, agree with Max that once codified, as PRINCE2 and MSP are, they cease to be best practice‚ and become just part of good practice. By definition Best Practice is something currently in use somewhere not yet codified. That is not of its own a reason to denigrate good practice‚ even when incorrectly named. Not all of us will want to take the risk of developing best practice‚ with the high costs involved and the risk of quickly being overtaken as others make continuous improvement. Technically, and to be as pedantic as Max, this should be continual improvement‚ i.e. improvements made in small or large incremental steps.
This is particularly true when looking at low and medium risk projects. These are where project margins are likely to mean that the organization would prefer tried and tested methods rather than experimenting with far too risky state-of-the-art new ones. Many, many years ago when I was with John Laing Construction working on housing projects with single figure margins, we did it by the book, rather than letting people try out new ideas!
On higher risk, or mission critical projects, it is probably more important to use highly experienced project managers to lead the project from first principles. Where the project is more innovative or novel, it might be possibly trying out some new best practice ideas. Indeed most Maturity Models insist that any centrally controlled process must be flexible enough to be changed to suit the particular project in order to achieve the higher levels of maturity.
Another benefit of using a standard approach to managing projects in larger organizations is that everyone speaks the same language, utilizes common templates, uses similar techniques and any handover of a project becomes much simpler. This is true whether the handover is provoked by the normal course of the project life span, by his or her promotion to even better things, or some other external event. In other words, there is continuity through the organization.