DFC, I can't understand your rather wooly reply. Are you claiming I lack common sense? I don't need patronising simply because I "dared" to question something you posted, as if it were a mandatory requirement. I'm looking back on a history of some thirty years flying for a living, much of it in poor weather below MSA and another five years of other aviation before that, so I do already understand the causes of CFIT to some extent.
The term "must", in CAA talk, means "mandatory", i.e. a legal requirement. You obviously apply weather limits well in advance of the legal requirements to your own VFR flights; your choice, and I can only say good for you.
However, it is important that folk don't read a post such as yours and think this pilot breached legal requirements in a major way by not applying "your" personal cautious VFR limits.