Hi @rp@n,
I don't think that there is a best way/situation when to use the water fall method and when to use the agile method.
The usage of the one or the other method depends on the company implementing D365FO, the culture of the company, etc. etc.
Currently the water fall method is considered being 'old school' by many.
Yet, it might be the best method that fits your company, your culture, the way people work.
It really depends on many factors what method to use and under which circumstances.
Because of that, I don't think that you will get a definite answer to your question here.
You have to find out what might fit best in your specific environment.
Best regards,
Ludwig
