Hi Don,
With 14 subjects, presumably you won't get to Subject Z
.
What you'll need before this can be progressed is a set of criteria for determining whether a given subject gets tested twice, thrice, etc, weighted according to the number of test sessions available.
Obviously, with 14 subjects, if the user inputs 7 days and, say, two tests per day, each subject can only be tested once. If you've got 10 days, though, that's another 6 tests that can be done, so what's the priority? Does one simply start at the top of the list and work down the first 6 tests, or does schedule, say, three of tests 1 & 2 two of tests 3 & 4 ...