Every pinned section is a promise that what happens next is worth standing still for. Most of them are writing cheques the content cannot cash.

The contract

When you take over the scroll, you have borrowed the one control the visitor had. The deal is that you give back more than you took: a reveal they could not have got from a static layout, a relationship between two things that only reads in sequence.

A test we use

Screenshot the start and end state of the pinned sequence. If a visitor who saw only those two frames would understand everything, the pin is decoration and should be deleted.

Budget

We allow ourselves two pinned moments per page. Scarcity is what makes them land.