Apologies for posting on an old topic, but it seems that this question gets a response every few months with no solution. I think I may have an answer you will like.
I'm the founder of eventcalendarapp.com. Our software lets you build an Event Calendar and then add it to your Squarespace page.
We offer all softs of features, but most importantly we have full support for recurring events. Everything you could ever think off:
Every day
Every week (and only on certain days)
Every 3rd day of the month
Complete custom dates of your choose
Honestly, literally anything.
I appreciate the downsides of using external software rather than something that is baked into Squarespace however the beauty of this is that we can do things that Squarespace can’t.
If you are interested, here is an example of a Squarespace site using Event Calendar App and recurring events:
https://www.westendchurch.org/calendar
Thanks everyone.