Spirit flex progression

[Skyfly]

It seems with Spirit poles, that the change in flex form pole to pole in 5lb increment poles is about 1.0. Is this generally true?

Is the flex progression inside the same length pole series linear? For example, if looking at 15 foot poles, would the difference in flex between a 140 and 145 pound pole be the same as the difference in flex between a 180 and 185 pound pole?

If the 1.0 flex difference is generally true, is it consistent with all pole lengths or do different pole lengths have smaller/larger flex ranges?

Thanks.