I practice yoga almost daily in a yoga center in my city. There's a limited number of slots for all lectures and you have to register in advance. You can unregister more than 2 hours in advance without any penalty - as a result, many people register to lectures days in advance and unregister shortly before the lecture if they decide not to go. Many of the best lectures are almost always fully booked.

At first, I made a simple notification bot that checks the website regularly and sends a Telegram notification once a lecture is free. Recently, I added a script that logs me to the lecture automatically, so I don't have to follow notifications. Simple and useful project.