FWIW, last time a similar promotion was run requiring two stays (IIRC), it was enough incentive for me to book exclusively at SPG properties while it was running. I booked quite a few more stays than I would have otherwise.
This time - three stays == 1 weekend night, not quite enough of an incentive for me to do that again. It's decent, but bringing back a recent promotion and reducing its value so much is certainly gonna get noticed by travelers like myself.
Still have much love for SPG. Just not gonna see as much of you as I did during the last iteration of this promotion.