The Customer Engineer Paradigm 

This is based. On pure common sense.

What is the " Customer Engineer " Concept?

Here, if one is making an enhancement or "trying" out a cure without professional help, it is adviseable to do it a step at a time.
For example, when an IBM Customer Engineer tries to resolve a problem, he takes out what he feels is a faulty `card'. He monitors the situation for a few days to a week and if the problem has been solved, this is ok. If not, he replaces another card and monitors again.
Similiarly, if you are doing some enhancements on your own, avoid doing all at the same time. For example, do not enhance the garden, a certain room or more at the same time. If something happens, you may not be able to know what you had done wrong.
It is good therefore that if you make an enhancement, try it for two weeks to a month. (Particularly for those who like to do enhancements on a frequent basis).