There are two types of ‘additional start times’: one is ‘repeating’ and one is ‘fixed’. ‘Fixed’ gives you three additional start times at specified times. ‘Repeating’ gives you more start times but they must be on a regular interval. With ‘repeating’ you can set how many times you want it to repeat, for example, 3.
If you have no more than 4 start times (including the first start time), you can use ‘fixed’ additional start times. If you need more than 4 start times, you need to use the ‘repeating’ start times. That’s it.