I used to live in a condo with some friends, and there were others in our friend group that would randomly show up throughout the day. The doors were always unlocked, so friends would just walk in. Sometimes it would be early in the morning and would hang out while I made myself breakfast. Sometimes it was late at night after they partied and needed a place to crash.
Seems similar to what you mentioned, I relate. Like you said, Friends was idealized, but not unrealistic.
Nowadays that mom would get arrested for neglect or some bullshit.