In my experience, it was not nearly sufficient. If your AC is appropriately sized (or undersized) for your house, you can't just drop several degrees in 2 hours during the hottest part of the day. Going from 78 to 72 to 84 in set temp looked more like 78 to 77 to 83 in practice. Granted this was in AZ in an older house, so extremely high outdoor temps combined with marginal insulation didn't help.

If they pre-cooled the night before it might be a different story.

I think a poorly insulated old house in Arizona is probably one of the worst-case scenarios here. Maybe there should be a configurable or learning-based pre-cool length, though.

This feature actually makes my house uncomfortably cold.