Q: over-intelligent calendar

Is anyone else irritated by the occasional behaviour of the time input facility on Calendar (for desktop, anyway)?

Say I have an event scheduled from 15:00 to 16:00 and want to change it to 17:00 to 18:00, so I overtype 15 with 17.

Sometimes it works as expected, but sometimes like this:

Calendar alters the time to 07:00, because 17:00 would be after 16:00, and we can't start later than we end, can we?

So I sigh and alter the finish time to 18:00, then go back and change 07 to 17.

But the (non existent) event from 07:00 to 18:00 would have been 11 hours long, so when I type in 17 Calendar changes the finish time to 04:00 (because it's being helpful! I must want to preserve the length of the event, surely!)

So I sigh again, change 04 to 18 - there we are at last. No, because of course we now have a two-day event!

Am I the only person seeing this behaviour? And I don't understand why it doesn't happen repeatably.