Several methods exist and refer either to standards or to intra-company practices. Each method has limits and advantages, of course, the best method is the one that responds to the problem, “how to succeed in my project in a minimum of time and at the lowest cost?” “.
This delicate mission of a company director, who in the process decentralizes him from his profession, has no solution but to resort to specialists in the field. This refocusing on its core business by avoiding looking for bad compromises can only delay or even abandon a project. There is certainly an advantage in doing things yourself, but at the expense of what other essential project which is to ensure the survival of the company.