Confimed. This code for instance was showing a model every 15 minutes for 15 minutes on the first day of each month. In MSFS2024 it shows the model for every 1st day of the month, but for the whole day:
(E:LOCAL DAY OF MONTH, Number) 1 ==
(E:ZULU TIME, minutes) 60 % flr 15 >= and
(E:ZULU TIME, minutes) 60 % flr 30 <= and
(E:ZULU TIME, minutes) 60 % flr 45 >= or if{ 1 } els{ 0 }