What is the 60 second rule in D&D?

Excuse me, could you please clarify what you mean by the "60 second rule" in D&D? Is this a specific gameplay mechanic, a rule of thumb for decision-making, or perhaps a commonly followed guideline among players? I'm curious to understand its significance within the context of Dungeons & Dragons, as I'm not immediately familiar with this particular term. Could you elaborate further, perhaps by providing an example or describing its application in a game session?