Let's think about this for a second, if you have a lantana that is nice and bushy and the night gets to say 30 degrees the outside of it might be damaged by the freeze. It has protected the core of the plant with the extra growth on the outside. These landscape companies that excessively prune them back into little flowerless ugly balls are simply ensuring job security by basically killing them in advance and making sure they will have to replace the plants in the Spring and be valuable to the people that they are employed by.
I would never tell anyone to do a severe pruning until Spring. Rarely does a plant ever even profit from any sort of such a pruning. The weather is more conducive to that sort of pruning in a warmer season. It is such a brutal practice especially out in the outer regions of the valley like Queen Creek. These large landscapers have really mastered the best business practices that they need to make sure they are in demand at all times of the year. A little bit of common sense would really tell anyone that you would leave the bushes and trees to have their "winter coat" on just like the animals get in the winter.