Importance of aptitude tests

[Mach E Avelli]

Kiwi we could argue when one SHOULD solo, and because of the variables, come to no conclusion. If you are doing 30 minutes every month, it could take a very long time because of the lack of continuity. If you are learning at LAX International, ditto, because of the ATC situation, or if your instructor is useless, or if you are learning on some really tricky taildragger aircraft at a really challenging bush strip, maybe. But most flying schools use docile aircraft with training wheels on the front at benign airfields, if only for insurance purposes.
In a normal world, a normal person receiving proper and regular instruction should be able to meet approximate milestones that have been developed from past experience. I don't have statistical data, but would hazard a guess that 12 to 15 hours is about average time to solo for a westerner who has had normal exposure to the mechanical age. Perhaps a poll is in order, where pilots could qualify with things like time out for illness.....
One of the reasons airlines which run their own cadet programs do progress tests early is to weed out the slow learners whom they cannot afford to carry. Why should they have to make special cases when competition is so keen? Unfortunately for the psycho-babble exponents, the only definitive aptitude tests for pilots that I have seen to be reliable involve flying an aeroplane!