I think I'm uniquely positioned to comment on this thread as I'm both a grocery store maintenance manager as well as a trade school student (refrig).
In 2008, my market converted to a whole new refrigeration system (Hussmann protocol). We were spending absurd amounts of money before the remodel on refrigeration service calls (we had a very old rack). After the install of the Protocol's, our refrig. expenses (4 years later) are almost zero as a % of sales. Thing is, if the cpc alarms, a manager will go and read cpc display unit (it's made so non-tradespeople can do it!). It clearly says something like "Meat Freezer--High Temperature". First thing they do is go and check the door-and close it. That type of thing takes care of ~80% of alarms. Before, they would have immediately called a service company. Not anymore.
Then, you have guys like me at stores. I keep the coils clean, and if something like a condensate drain backs up, I do the work. Before, it was the refrigeration company. Not anymore, at least at my market.
That leaves only the complicated stuff that my store is *willing* to pay truck charge+labor for. And with the reliability of our system, we almost never dial that number anymore. And, our energy usage is down by a huge amount vs. our previous system.
When I think of they above, I really question why I'm shelling out $15,000 for trade school at all. Grocery store managers want to minimize labor expenses at all costs and companies like emerson climate will listen. Pretty soon they'll make a cpc that's so user friendly you won't need a tech at all.