But we're back to the question I has several million posts ago: what do you do if the PCs decided to break into a house as a whim, not as part of a plan? Unless you are a world-class railroader, the PCs are sometimes going to want to do things you didn't plan for--and that sometimes may be a lot of the time. And that requires improvisation.
There's no reason for there to be Godzilla in a closet, though, because there's nothing in the fiction that would allow Godzilla to exist there at all (assuming that closet-sized kaiju are not a thing in your world). That's what people keep forgetting--the fiction. Does it make sense, considering the time, location, and other factors, that this thing exists here? Yes or no?