For the best result, use 5 minutes intervals, 0 ,5, 10...

Start time and end time: All periods will be calculated in whole intervals of 5 minutes. Regardless of the choosen start and end time.

Gap: Must be less than the interval between start and end time. If not the time will be displayed in red and an alert wil be shown. Gap will be usede between all periods.

User-defined period: Choose 1 of the 3 periods to be longer or shorter than the calculated periods. The choosen time must be less than the time interval minus the gap. Otherwise an alert wil be shown and the choosen time wil be displayed in red, and periods will not be calculated.

User-defined periods: Choose 1 - 4 periods to be longer or shorter than the calculated periods. The choosen periode length multiplyed by number of periods, must be less than the time interval minus gap.
If the user-defined period is to long, time will be red and an alert will be visible.
Periods wil be calculated when user-defined is within range.

Useer-defined gap: Choose 1 of the 3 gaps to be longer or shorter. The User-defined gab must be less than the time interval minus gap and user-defined periods. An alert wil be visible and time will be red if user-defined gap is outside the range.