Thanks Richard,
What I meant was if a aircraft (second aircraft) decides to land behind another aircraft having already landed, the first aircraft now could have issues in making a decision about whether to backtrack after landing as required or being forced to depart via a closeby taxiway if available.
As far as I was aware this was separation minima for landing, rather than taking off.
I got the point of your other post though - the term you used well in the book regarding separation was good but almost a political one re VFR separation from other VFR where the pilot must comply as ATC are not "in control" - it was "procedural separation".
I really like the idea of "actual separation" heaps better
see and avoid has its flaws...
Thanks for your views on sufficient distance, as you say its a judgement call, but it seems even in aviation common sense doesnt always apply...