But when adjudicating situations in a "realistic" setting, the lack of procedures for establishing relevant fiction manifests itself pretty quickly. Players with Waiting Illusion on their spell lists naturally look to the use of this to create alarms and warnings. Which then requires the GM (ie me!) to determine all the stuff we've been talking about in this thread, in respect of distances, timing, methods of infiltration etc. And it all just has to be made up.
To circle back a bit, I think the mode here is important. I'm finding myself becoming more free with fiat and more exacting in my extrapolation of what exists in terms of the fictional circumstance.
I think one of the big differences though is that you don't need to keep hidden information quiet so hidden because it's not a part of the strategic game loop.
I know that Henrik is after the party so I frame a scene where they are camping. The Wizard sets a magical alarm and I'll flat out say 'I don't think that protects you from missile attacks, if someone suspects you've put an alarm up.' And the implication is that I'm not asking this for my health, there's a guy who suspects they put an alarm up and has ranged weapons on the way to the camp.
'well my guy is exacting, is there a way to set up the alarm such that it might catch a ranged attacker?'
'Well it's forest so it might be a bit of guess work, some kind of wits v wits. Although wait, would you camp in the forest then, or would you specifically try and find terrain that allowed you to leverage the spell?'
'I would find terrain.'
'So how about we roll wilderness to see if you can spot some suitable terrain within a reasonable time frame'
'sounds good'
we roll and they fail
'So there is suitable terrain if you backtrack for an hour or so but you can't see any around here so all the stuff I said about camping applies, we'll do a wits v wits.'
I'm just roleplaying with myself now but this is kind of how I do it. The fictional stuff matters but there's a load of fiat involved as well.
EDIT: Anyway my point is that I agree with you. You have to make up your own procedures to get to functional.