When one uses "Start At" to run a query multiple times, each returning a sub-set [Items Per Page] there is a very high risk of either missing items, or getting the same items twice.
Consider a trivial example where the total returned data would be:
A,C,E,G,I,K
A page size of 3 would return ACE on the first call, and then a StartAt of 3 would return GIK on the second call..
However, things go bad if either of the following occur between the first an second call...
* - "C" is deleted... The second call returns only I,K and G is missed
* - "B" is added... The second call returns E,G,I meaning E is returned twice.
