This is all to say that the Foundation realm was a rather odd one, as it was about mixing the two forces in one's body to create a new balance that would allow for further development.
The Foundation realm could be long or short. You could, in theory, skip to the Golden Core realm as long as one singular spot of Qi had combined with the body as long as you were talented enough, but nobody would do this, as as the name of the realm may imply, the Foundation realm relates to your basics.
If your Foundation is unsteady, no matter how high the building is built, in the end it can only collapse.
As for the last unmentioned spot of Qi, it was unmentioned because it was only possible if all other 9 spots of Qi had already been combined, and it was combined with the Nascent Soul, which would create a Divine Soul, thus bypassing the extreme of nine and approaching the Divine Ten.
