Re: A word on Time Trained and Ranking
I think up to sandan hours/days trained are important.
Put simply 0 - sandan is almost purely technical i.e. how well can you perform the standard techniques. Thereafter the Aikidoka should begin to show some depth of understanding - then it makes sense to impose a number of years between eligilibity for promotion and a much looser (in some ways more subjective) grading system.
So if we are to apply the above provisos and follow generally accepted sports science guidelines we get around 10,000 hours up to sandan (technical proficiency) and an open-ended time qualification for "higher" ranks