Bob.. i have a feeling you only print on 2 different materials....
You'd be wrong, by a long shot.
...This advice is terrible...
That would depend very much on whether or not you regard what comes out of the printer as the truth or what appears on a monitor to be the truth. If the latter then I agree, bad advice. If the former then it's been working flawlessly for me on a myriad of media over the last 9 years or so.
The biggest problems I had when first venturing forth into large format printing was not completely understanding that what comes out of the printer is the truth. Thing was, I understood it well enough, I never set up the work to accommodate it. Once I figured all that out, things became relatively simple and straightforward.
Every profile has different heat settings, ink coverage, different printing speeds, and different coloring.
Micro differences for the most part.
If you know what your printer is going to produce with profile X on media Y then there's little need for all of the other minutiae unless that sort of thing gets you off. If you really think that cranking one of your heaters a few degrees one way or the other is going to make everything all right you're kidding yourself.
The biggest factor in what comes out of the printer is the white point of the media. Even that isn't all that much until you start printing on media that most definitely is not white. Like silver and/or other light colored vinyl.
I've printed my trusty Pantone chart using the same profile on two media that were both white but were two visibly different whites and resultant charts on each media were sufficiently the same to call it a draw.
The point is that if you adapt your work to what your printer does in given circumstances your life becomes far simpler than if you insist on your printer adapting itself to your work. It's somewhat like removing a light bulb by turning the room or merely turning the bulb.
This notion generally causes color theory, calibration, and profiling aficionados to become apoplectic which, being an iconoclast, in and of itself is not a bad thing. Anything which discomforts the smug is to be cherished.