I've worked with hotels' group sales departments to rent out meeting rooms for half a day to meet with a few other people. I don't think it's correct that they deal exclusively with large groups or events.

That said, I doubt this kind of thing is meant for an individual booking 30 nights in a given time period, and even less likely that 3 separate stays of 10 nights each would be an option to take advantage of this.

Also, these advertised perks are likely on the low end of what you'd get if you just start a negotiation from scratch.