They MIGHT check 1 out of 100 people once during the period I guess. But even that is unlikely. However, they rely on the good-old neighborly vigilance and especially the porteros to enforce it SO if you live in a building with no portero and have good or no neighbors then all is good.Cruising to the finish line on my wife's quarantine. So far no one has checked. No one checked on me either when I returned in June.
Do you actually think someone would check? That would take effort and resources.