18 May 2026

What a shrinking diagonal is allowed to say

People like the look of a diagonal. Each step to the right is a later week for the same intake. When the cells get paler, a meeting often jumps to “people leave.”

The diagonal only says fewer of those labelled week-0 people appeared in later weeks, under whatever return rule you chose (any open, a session of substance, a purchase). It does not say they uninstalled, or that a competing app won, or that a paywall was the moment.

If later weeks are still empty because the intake is young, the diagonal is unfinished. We write “cells not yet due” rather than drawing a curve through blank paper.

A sitting spends more time on the first disagreement about the return rule than on decorating the fade.