Glossary
What is vertical work?
A delivery stream owned by a single team or discipline that produces end-to-end value within its own lane — frontend, backend, data, mobile, platform.
Verticals run in parallel with each other and consume capacity continuously, as a rate: this team, this fraction, these months.
Vertical vs horizontal work
A vertical is a lane that can finish on its own: the backend stream, the mobile stream, the data stream. A horizontal is a concern that cuts across those lanes and gates them at specific points: security review, legal, accessibility, privacy, design. The difference is not size or importance, it is shape — one consumes capacity as a rate, the other in bursts triggered by someone else's progress.
Planning both with the same object, usually called an epic, is why cross-cutting reviews are such a reliable source of late-stage delay. Averaged across a quarter a horizontal looks small, so it gets a small allocation; in practice it arrives as three streams needing the same reviewer in the same fortnight.
How to size a vertical
As a rate against one team's capacity line: this team, this fraction of it, for these months. That form makes it directly comparable with everything else that team has already promised, which is the whole point of sizing at the commitment altitude.
It also makes the failure visible. When the fractions across all committed verticals exceed one team's line, the plan is over-committed, and it is over-committed in a specific named place rather than "somewhere in engineering".
Related terms
- Horizontal work — A cross-cutting concern that pulses into several delivery streams at specific gates — security review, legal, compliance, design, accessibility, privacy.
- Readiness (three-state) — A planning dimension has three states, not two: not assessed, assessed and nothing found, and assessed with items.
- Time-boxed discovery — A deliberate learning step taken instead of a decision: a goal, optionally the questions to answer, a time-box, and a target date on which it must conclude with recorded findings and an explicit decision.
This definition comes from building DeliverySheet — it takes a vague work request to a clear delivery decision, so the shape, owner, capacity, dependencies and open questions are on the table before anyone commits people or a date.
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