(These replies are getting too deep(!))
A monthly event happens once a month. (Why should such an event last whole week?) It could be that I do not have the same cultural background as you do related to calendar and time.
I'm not saying anything about how long an event lasts (or anything cultural/how time is divided); it's about how the recurrence interval 'zero point' is defined... and its inconsistency. Have another look at the examples I quote: (we're guessing) one uses the relevant 'zero point' for the next smallest 'time division' (use the '0th hour' as the starting point for a 'day' recurrence), while the other example does NOT use that convention (you'd expect the '0th week' (or '0th fortnight') as the starting point for a 'monthly' recurrence)... but that's not how it works -- the rules are inconsistent.
Hence, I'd suggest it would be helpful to include a table in the docs that defines the 'zero point' of the 'beginning' of each 'recurrence type'... so that users of a 'recurrence type' would be more likely to understand the actual workings of the recurrence.. instead of needing to spend time trying to deduce how the recurrence is working.