Typical drop-ins work as follows, with variations from week to week:

• People show up at will on Saturday mornings – how many show may vary from week to week.  Ideally, you should show up a few minutes early to warm up before play begins
• Doubles is the objective.  The initial team assignments may be made by the organizer, although this process can be more ad hoc
• Play is organized in rounds, typically 30 minutes in duration.  At the end of a round, which often occurs before a set is completed, winners are determined.  Various ways are used to determine winners if the game score is tied when the whistle blows.
• Then there is a “shift change”.  For example, when the round ends, losers of a round may move to the adjacent court to the East and winners move West.  Then, to make things interesting, the new court assignments are swizzled, such that no two players are on the same team twice.  The effect is that over say 4 rounds, you will have a chance to play with 4 different partners.
• Rinse, lather, repeat for two hours or so.  Some variation should be expected depending on how many participants we have.  There is often opportunity to play some singles as well, for example

See you on the courts!