Have you ever had something ingrained in you so deeply that you are shocked to find out it may not be all that true? Some examples from me:

You should never mix refrigerants: Look at the mixtures that are out there today!

Gas defrost is superior to off-time defrost for fresh meat display cases: There are those who now believe that off-time defrost keeps better product temperature!

Using an EPR in a service meat case will provide the best humidification: There are those who now say that cycling on a thermostat will provide better humidification.

For me, seeing things held so dearly succumb as "old wive's tales" makes me wonder about what else I believe that may not be true. For example:

That parallel racks are inherently more efficient than conventional single unit applications: I ain't so sure anymore.

That gas defrost is more efficient than electric defrost: I ain't so sure anymore.

That heat reclaim from discharge gas is "free" heat. I ain't so sure anymore.

Of course, these are simply narrow observations from a supermarket guy.

I keep thinking how many different ways I was taught to brush my teeth, that eggs, salt, aspirin, and pork were bad for me and then later good for me, and back and forth.

I wonder if there are more instances that others could share - within the trade, of course, of having a firmly held belief just doing an about-face on them as the world goes on?