Looking again at the title to your thread:- "Manufacturers recommended" -versus- what-have-you ...
Of course manufacturer recommendations should always be respected and considered, but the trouble with simply following such words of wisdom is that they can vary greatly (in terms of both quality and practicality) from manufacturer to manufacturer, even within equipment of similar (or same) type.
That is why I have always advocated developing PM procedures in-house. In a word:- consistency.
