Out of the box LE make it hard to actually achieve that most basic of calendar fails.

As far as I know, Let's Encrypt themselves do nothing to prevent you from hitting the expiry date with your certificates, but then I'm not sure what you mean with "Out of the box Let's Encrypt".

Usually you run Let's Encrypt with something like EFF's certbot, and then you certainly get lots of help to have up-to-date certificates, as long as you installed it in a way so it automatically runs (via cron or whatever you use).

I get emails from LE when my certs are about to expire. I'm honestly not sure how they do it (based on the email address, I'm guessing that they pulled the email they are using from WHOIS), but it's not something I went out of the way to set up.

I really like it, because it lets me know when I need to go in and kick certbot.

You likely gave certbot the email address when you set it up first, and it registers it with LE.

I've used LE for a few years and multiple times Certbot has broken, needed to be reinstalled, reconfigured from scratch, etc. In theory it keeps things updated automatically, in practice it needed a lot of wrangling.