The current scheduler Mendix uses to schedule and execute scheduled events has a lot of limitations and will result in unexpected and undesired execution moments of scheduled events. See also the documentation
From the documentation: "Seconds, Minutes, Hours, Days, and Weeks are scheduled exactly as configured. However, Months and Years might not be executed as you would expect. A month is interpreted as a 31 day interval, a year as a 365 day interval."
From the documentation: "Whenever you set up an event to run every day at a certain time, it will start at exactly the specified time. However, after this it will run at a fixed interval (internally this is calculated back to run every X nanoseconds). This means that a daily event runs every 24 hours. Therefore, if the time changes because of daylight saving, your event could be an hour off."
So, please improve the scheduler!
See also this idear: https://forum.mendix.com/link/ideas/230
And for daylight saving time you need two schedules each with its own microflow that checks if DST is active or not (see community commons Java action).