Commit 7-8 hours when you have 10 available — leave 2-3 hours of slack to absorb disruptions without cascade failures

Why This Is a Rule

A 70-80% commitment rate is the sweet spot for daily capacity planning. Below 70%, you're underutilizing your productive capacity — too much slack becomes wasted time. Above 80%, the schedule is fragile: any disruption (unexpected call, task running over, energy dip) cascades through the remainder of the day because there's no absorption capacity. At 100% commitment, the first disruption collapses the entire plan.

The 20-30% slack serves the same function as One 15-minute overflow buffer per 2-3 hours of scheduled activity — absorbs overruns and prevents cascading disruption's overflow buffers but at the macro-daily level rather than the micro-session level. One 15-minute overflow buffer per 2-3 hours of scheduled activity — absorbs overruns and prevents cascading disruption provides 15-minute buffers between sessions; this rule provides 2-3 hours of unallocated capacity across the entire day. The two work together: micro-buffers absorb session-level overruns, macro-slack absorbs day-level disruptions (unexpected meetings, emergencies, energy crashes, tasks taking 2x longer than expected).

On days where no disruptions occur, the slack becomes bonus capacity — time you can use for low-priority tasks, skill development, thinking time, or simply ending the day early. This makes the slack feel valuable rather than wasted: it's either disruption-absorption when needed or bonus time when not.

When This Fires

• When planning your daily time blocks and deciding how much to commit
• When your days consistently run over because every minute was planned
• When you finish the day with half your planned tasks undone despite working steadily
• Complements One 15-minute overflow buffer per 2-3 hours of scheduled activity — absorbs overruns and prevents cascading disruption (15-minute overflow buffers) with the macro-level daily slack ratio

Common Failure Mode

100% utilization planning: "I have 10 hours, so I'll plan 10 hours of work." This works perfectly on paper and fails in reality. The first disruption (which is guaranteed on most days) has nowhere to go, so it pushes everything else back. By 3pm you're behind, by 5pm you're abandoning tasks, and by evening you're demoralized by the gap between plan and reality — a gap caused by overcommitting, not underperforming.

The Protocol

(1) Determine your available productive hours for the day (total waking hours minus meals, commute, personal care). For most people, this is 10-12 hours. (2) Commit to 70-80% of that number: if 10 hours available, plan 7-8 hours of specific work. (3) Leave the remaining 2-3 hours as unallocated slack. Do not assign these hours to specific tasks. (4) As the day progresses, use slack for: absorbing overruns, handling unexpected requests, bonus work if the day runs smoothly. (5) Track: what percentage of days used the full slack (disruption-heavy) vs. had surplus (smooth days)? If you're using all the slack every day, either increase slack or reduce commitments. If slack is rarely needed, you might be able to tighten slightly — but err on the side of too much slack rather than too little.