IIRC the soviet air force in East Germany had fixed "flying days" for every military airport. Say tuesday and friday for some example air base. Flights would only happen on those days. They just had too many air bases to coordinate. Sometimes they would be done for the day by late morning, sometimes they would do refuellings and take off again or do night flights later on. Most flight were local patterns or very limited firing range and back flights. Not many cross countries. Comms were preset before a flight by mechanics and could only be changed very limited by the pilot later on. Sometimes they had to use a certain ammount of fuel during a plan period. If not all had been used for some reason it would even be spilled or burned intentionally on the air base to be able to report the fuel use orderd from above.
Interesting site to get started:
https://16va.be/blinder_over_berlin_eng.html