Air carrier Captain reported ground deicing procedures at MSP and different types of de-ice fluid are being incorrectly applied.

Narrative

I was recently in MSP during a snowstorm. The de-ice crew informed me that they would apply deice/anti-ice fluid at the gate. We configured after getting pushed back with engines off; APU on due to fan blade icing present. I noticed that while the truck was moving behind us that my left wing was green; but the truck hadn't reached the right side of the aircraft yet. This perplexed me. When they 'finished' and read back the information for the type IV; the time was nearly the same time they started with the type I fluid; and they only circled the plane once. I queried the crew; who informed me they applied type I to each section; and then type IV to each section; before moving to the next section of the aircraft- putting type IV fluid onto a hot surface. I have never heard of this application before; as neither had my FO nor anyone I could get a hold of with more experience. I asked the crew to re-apply the fluid in a more consistent manner that every other station I've ever seen used. There was considerable pushback from the deice crew; requiring me to make it clear that as the PIC it was my call. Upon landing in ZZZ; I called the Chief Pilot; who had also never heard of this application style. He later called me back after returning to MSP explaining that it was an approved technique. If this is true- it needs to be documented in a manual that is available to pilots. Applying type IV fluid to a surface that *should* be very hot from type I congeals the fluid and reduces its effectiveness. After reading several FAA publications on the application of type I/IV fluid; I believe that the MSP crews are incorrectly applying it.