On Sun, 30 Sep 2012 23:35:13 -0400, Jan Philips
wrote:

If A11 had failed to land, how soon could the next attempt have been?
One month, two months, other?

It would have depended on what caused that failure. A major mechanical
failure would likely have taken many months to find and fix.

Apollo 12 was on the books for September 1969 and Apollo 13 for
November, so they theoretically had two more chances to meet the 1970
deadline.

Brian