Why would it warn you if you didn't need support but have it anyway? There are things you can make without facilities, so it stands to reason that within facilities you wouldn't be hindered in any way.
Maybe (and I'm saying maybe, but I don't believe it) higher tier support helps if you required support at all. From my experiences however, I can just as easily make cotton cloth with common support as well as master support (including a random break every now and again). And I can just as easily fail Canvas with common support as with master.
So do yourself a favour and don't get support unless you need it, and stick to the required support. However, feel free to get higher tier support if you're paranoid or believe it works.
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