Bulgakov himself lived at Bolshaya Sadovaya ulisa number 10 in Moscow for a while with his second wife. From the list of tenants of that building we know that apartment number 50 was shared with other people.
The shortage of living space after the revolution created the typiscal Soviet phenomenon of the коммунальная квартира (kommunalnaya kwartira) or communal apartment in which families had one or two rooms for themselves, and shared the kitchen and the bathroom. Often there would be resentments between the various families living in one communal apartment.
This phenomenon is beautifully described in the movie picture [Est] Ouest or [East] West by the French director Régis Warnier, starring Sandrine Bonnaire, Oleg Menchikov and Catherine Deneuve from 1999.