About Variable Font Origin and the font file size

Glyphs
1

The Glyphs handbook says “Since the regular master tents to sit in the center of the designspace, it requires more deltas to describe the other masters. This increases the font file size compared to picking a corner master like Light or Light Condensed .”

But among my test fonts, that using Regular master as the origin is the smallest and I want to know why?

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(From left to right are VFO set at Thin Regular and Bold master)

2

It often will be a bit smaller, not always. It depends on how the points are arranged in the masters.

3

I want to know the relationship between the points and the VFO which makes the file size smallest but it seems too complicated. Anyway thank you @mekkablue .