The difficulty of tailoring
To be honest, tailoring is complicated! Some people simply start cherry-picking from various project management systems and call it tailoring, whereas what they create in this way won’t have internal consistency and usually doesn’t work well. In many cases, it resembles Frankenstein’s monster! In general, when tailoring, we’re building a new system, and like any other system, we must take a holistic, critical view.
Most systems leave the responsibility of tailoring to the project manager. However, someone who is an otherwise great project manager may not necessarily have all the skills required for building a system. It’s simply unrealistic to expect every project manager to have such a range of skills. Something interesting in DSDM® (a project management methodology built for Agile projects) is that they’ve identified this problem and assigned this responsibility and a few others to a separate role they’ve called the DSDM Coach.