Do some people here think that a scale which for example goes from G, up to G, and up to a THIRD G, is called a three octave scale.

It is not. It covers only 2 octaves, an octave being 8 notes of a typical scale, or a doubling of frequency.

Seeing the range of a flute is form low C (or B) up through three octaves, and then on to the FOURTH F which is the 7th ledger line, it is possible to play three octave scales starting on at least any note from low C (or B) through to the second space F on the stave.

To make this quite clear for those who have not learnt many notes yet, each of these covers 22 notes going up the scale - i.e. 7 for each octave and another after the third octave.