Any page with more than six stamps on it is a blessing for those trying to conserve pages.

I think agents are taught to not stamp over other stamps, but I don't see why a little overlap should be a problem so long as the dates are readable, esp. since they often stamp the exit stamp partially over the entry to show the connection between the two.

Old Thai agents may have learned to be haphazard when they had to also stamp the no longer used TM6 cards, which was literally twice the work.