My client Saša was convinced that she couldn’t possibly work in time boxes. She was always interrupted by subordinates . Her observation was that it’s a part of her manager role to be at the heart of things, to always be prepared to help others. In the latter, she was right.
We tried that she blocked an hour after lunch every day in her calendar. We called it the volunteer hour. When colleagues requested her helping hand during the day, she — instantly without dissecting the problem — scheduled a 15-30 minute meeting in her next volunteer hour.
The concrete and simple action plan, made her interruption recovery smooth and quick. No momentum was lost for the task she focused on before she was interrupted. On days where no requests for help appeared, she spent her volunteer hour on discretionary work.
Naturally, there are exceptions. When Saša could answer a question from the top of her head, she did so immediately. Sudden high-risk tasks also had a higher priority than her volunteer hour strategy. But, how often can a task not be deferred a few hours?
Already after a few weeks, Saša told me how successful the volunteer hour strategy is. She used it also for incoming phone calls that required more thoughts and discussions. An added bonus was the fact that the Zeigarnik effect  let her subconsciously process the task ahead.
 Wajcman, Judy, Rose, Emily – Constant Connectivity: Rethinking Interruptions at Work, Organization Studies, vol. 32 no. 7 941-961, July 2011.
 Zeigarnik, Bluma – Das Behalten erledigter und unerledigter Handlungen. Psychologische Forschung 9, 1-85, 1927.