Work exclusively on the top-of-stack item until it completes or blocks — 3-5 items max, serial execution, not parallel distribution

Why This Is a Rule

A priority list of 15 items is not a priority system — it's a to-do list with labels. The term "priority" means "that which comes first." If more than 3-5 items claim first-place status, nothing is actually prioritized. The 3-5 item maximum reflects working memory constraints: you can hold 3-5 items in active awareness simultaneously. Beyond that, items become invisible — they exist on the list but not in your active attention.

The serial execution model — work exclusively on item #1 until it completes or genuinely blocks — prevents the attention distribution failure. Parallel distribution ("I'll work on all five a little each day") produces context-switching overhead (Calculate activity cost as disruption footprint: ramp-down + activity + ramp-up — the true cost includes attention residue) that consumes 20-40% of available time while giving each item insufficient focused attention to make meaningful progress. Serial execution on item #1 gives it 100% of available attention until it's done, then item #2 gets the same treatment.

"Genuinely blocks" is the escape hatch: if item #1 is waiting for external input and you can't advance it, rotating to item #2 is appropriate. But "I feel like working on something else" is not a genuine block — it's preference, and yielding to it restores the parallel distribution pattern.

When This Fires

• When managing daily or weekly work across multiple priorities
• When you feel scattered across too many priorities — reduce to 3-5 and serialize
• When important projects aren't advancing despite "working on them" — parallel distribution is likely the cause
• Complements Draw the line after item 3 — peak attention hours go above the line, everything below gets leftovers or explicit deferral (top-3 peak allocation) with the serial execution model

Common Failure Mode

Parallel distribution across the full list: "I'll make progress on all 8 priorities each week." Result: 8 items each receiving 5 hours of fragmented attention, none receiving the concentrated 15-hour block that would produce a breakthrough. Serial model: item #1 gets 15 hours until complete, then item #2 gets 15 hours. Same total time, dramatically different results per item.

The Protocol

(1) Maintain a visible stack of 3-5 priority items, ranked by importance. (2) Work exclusively on item #1 until it completes or genuinely blocks. "Genuinely blocks" means: external dependency you cannot resolve, information that hasn't arrived, or a required collaboration partner who's unavailable. (3) When blocked on #1 → rotate to the highest unblocked item. When the block resolves → return to #1. (4) When item #1 completes → item #2 becomes the new #1. Add a new item at the bottom if appropriate. (5) Never work on a lower item when a higher item is unblocked. The stack order IS your attention allocation plan.