Opening the book…
The work we're actually paid for, thinking hard about difficult problems, requires long stretches of uninterrupted concentration, and those stretches are the first thing a busy team accidentally destroys. Deep focus takes time to reach and shatters in an instant, so a day sliced by a meeting here and a 'quick question' there can pass in a blur of activity with almost nothing real produced, because you never got deep enough to make progress. Attention is genuinely our scarcest resource, more than time or money, because a well-rested engineer with four uninterrupted hours can outproduce the same person with eight fragmented ones. We protect focus deliberately, as a team norm, because left to entropy the calendar and the notifications will chew it to pieces and everyone will wonder why nothing ships. Treating interruption as free is the expensive mistake, and treating focus as sacred is how a small team does the work of a larger one.
Guard your own focus by blocking time, silencing non-urgent notifications, and going genuinely heads-down, and defend those blocks as real commitments. Respect others' focus the same way: batch your questions, prefer async, and think twice before you tap someone on the shoulder for something that could wait an hour. As a team, keep norms that make deep work possible, no-meeting stretches, an expectation that channel messages don't demand instant replies, so nobody has to sit on high alert all day. Notice the difference between busy and productive, and optimize for the second, since a day full of responsiveness can be a day empty of progress. When you must interrupt someone, make it worth the cost by being clear and concise. And build in the slack that lets focus happen, because a fully-booked calendar has no room to think.
Focus isn't a license to be unreachable; part of the deal is being responsive at the boundaries of your deep-work blocks and dropping everything for a genuine incident. And some roles and some days are legitimately about responsiveness and coordination, so calibrate rather than treating every interruption as an outrage.