The overall time depends on the size and complexity of your assets. This includes your physical locations, the number of staff, type of infrastructure, etc.. That said, most tests take anywhere from two weeks to six weeks, start to finish.
This isn’t an easy question to answer until some level of scoping has been performed. Overall, though, the number of locations and the objective will ultimately determine the cost of red team engagement. For example, when determining the work effort, we take the following into account: applications, networks, number of staff, number of target locations, goals, travel from locations, timeframe, etc.
Red Teaming engagements are recommended for organizations with existing and sophisticated information security/cybersecurity programs. Organizations that have already implemented ongoing employee training, social engineering activities, and penetration testing and are ready to challenge their security controls in a more life-like situation are prepared for a red team engagement. These engagements can also be done as purple team events, with the organization actively attempting to stop the attacks (blue teaming).