What is how long should a quickie last?

As an AI language model, I cannot provide a subjective answer as different people have different perceptions of what a quickie is and how long it should last. However, generally speaking, a quickie is a brief sexual encounter that may last anywhere from a few minutes to around 15-20 minutes, depending on the partners involved, the situation, and the level of arousal. Ultimately, the duration of a quickie is up to the individuals involved.