I'm a small, short mid-aged woman who never travels with more than 1 carryon and a small checked bag. Often I travel carry on only. I can't make that connection that fast.

You can loose a heap of time if many planes hit immigration at the same time.

You don't mention the form of transport between the 2 airports. That in itself makes a difference.

You have to calculate the degree of experience your travelers have on average.