[susam]

Indeed! It's said that no talk should be longer than a microcentury.

https://www.ams.org/notices/199701/comm-rota.pdf

https://susam.net/microcentury.html

[fouc]

Nice one! I would've said half a microcentury would be the perfect limit for most school lectures, but for an engaging talk a full microcentury would be acceptable :-)