The RadCalendar renders six rows for the dates because for some moths there could be couple of days on the first or the sixth row (check June 2014 for reference).
If some of the rendered rows are removed and the RadCalendar is placed in milti-month view
the different months would not be aligned.
In case you would like to modify the number of rows that are rendered for the RadCalendar you would need to use custom logic that calculates if there are dates in all the rendered rows and remove the ones that are not needed.
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