The danger with the Ace student who goes solo after very few hours is he/she has not had the opportunity to make enough mistakes to learn from and be corrected by an instructor. These will no doubt appear later in flying when there will be no instructor to assist.
Any figures for 1st solo flight hours are likely to be influenced by the fact that some schools have insurance requirements that insist on a minimum number of hours before the 1st solo flight.
cheers
MJR
