Principles are ways of successfully dealing with reality to get what you want out of life.
Ray Dalio, one of the world’s most successful investors and entrepreneurs, cites principles as his key to success.
Sometimes hiring an external consultant is the best fit for your design. Doing so can get you precisely the amount of specialized expertise you need to tackle a problem. When you can outsource you don't have to worry about managing, and that's a real advantage. If a position is part-time and requires highly specialized knowledge, I would prefer to have it done by consultants or outsiders.
At the same time, you need to beware of the chronic use of consultants to do work that should be done by employees. This will cost you in the long run and erode your culture. Also make sure you are careful not to ask consultants to do things that they don't normally do. They will almost certainly revert to doing things in their usual way; their own employers will demand that.