Why I Banned Slack on My Team

Real-time chat is the enemy of deep work. A channel that expects an answer in minutes turns every engineer into a monitor — one eye always on the unread badge. That's not collaboration — it's a context switch your brain pays for every few minutes, and you can't solve a hard problem inside it. So, leading an engineering team, I did the unthinkable. I banned Slack. We went fully async. Documentation first. Long-form writing. Code comments. Pull request descriptions that actually explain the decision. The rule was simple: if it's urgent, call. If it's not, write it down and wait. ## What I actually measured A claim like "3x more deep work" is worthless without a definition of deep work. So we defined it before we changed anything, and measured the same way for six months on either side of the switch. We called the unit a Focus Block Hour (FBH): a continuous block of at least 90 minutes, no meetings, fewer than two interruptions, with verifiable technical output at the end. Measured at the team level, in aggregate — no screenshots, no keylogging, no per-person surveillance. You don't need to spy on people to count whether the conditions for focus existed. You need an honest definition and the discipline to apply it. Before the ban: **1.6 FBH per developer

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