So, at least 30 seconds, I guess?
As said, rather make it configurable. This is a real-world system… 😄
The ICS file 1 generated from the following Google Calendar resource 2 displays the wrong calendar dates. Namely, it displays two events on e.g., February the first instead of one at February 3rd and February 14th.
Looking at the ICS file we can indeed see two VEVENTs with DTSTART at 2022-02-01. However, they lack a RECURRENCE-ID, I don’t know what that implies. A similar non-recurrance-id event is created for 2021-11-29. If we remove all such entries, we are left with the “real” events that are actually supposed to be displayed. These, however, are ignored by ICSx5. Note that this 3 online viewer does display these events, however it also shows the “wrong” events at 2022-02-01.