Good thing is that the smell does fully go away even if you don't get to it. My house had a problem with mice in the attic and walls, but there was no patching fix that could reasonably done, since this is an old and pretty drafty house. They can really slip through the smallest cracks, even underground, and there had to be a hundred of cracks like that. Putting up and swapping snap traps was a pretty onerous task that never seemed to fully work.

The pest control crew that did fix the problem did so by putting a bunch of slow-acting poison bait traps around the property and in the attic. 3 days later some seriously awful smells popped up throughout the house, but they went away after a little over a week. Those mice are part of the building now, but I've completely forgotten about them.