Why do programmers need private offices with doors?

Two types of work exist: harmlessly-interruptible and "Do Not Disturb" tasks. Interruptions to Do Not Disturb work can significantly reduce productivity, as these tasks require sustained focus and mental effort. A 30-second interruption can potentially halve productivity for complex tasks. Open-plan offices may hinder Do Not Disturb work, while private spaces can boost productivity. Managers should protect employees' uninterrupted time for important, focus-intensive tasks to maximize creativity and output.