In the last quoted sentence you describe a procedure. (Or at least a fragment of a procedure.)You are the one that keeps insisting that there must be procedures spelled out in the rules that restrain the options of the GM for it to be a sandbox. If there are procedures and rules designed to restrain the GM's power that's ... wait for it ... procedural restraint.
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even if it is improvised on the spot it will hopefully be based on a knowledge of the situation and any NPC involved.
And you posit it as a desirable thing ("hopefully").
So I don't know why you keep posting as if you are disagreeing with me about the importance of procedures!