Once the edit leaves a scene, it does not go back.

Studio, street, studio. Nobody decides that — it falls out of grouping clips one at a time — and in a timeline it is close to invisible, because every individual cut looks fine. Written down it is not arguable at all. Take the scene label of every clip in playing order, compress consecutive repeats into runs, and any label occupying more than one run is a place the edit went back to. Three scenes should give three runs. This page counts them.

The engine is free and needs no account. Paste the clip pool and the grouping, and it does the arithmetic a grouping is supposed to satisfy: every clip used exactly once, which makes a clip lost between passes and a clip pasted into two groups two different findings rather than one vague sense that the count is off. It also keeps a continuous action — a bag coming out of a box in three pieces — inside one group or its neighbour, checks each group against its length and its clip count, and catches the stale id from an earlier pool that no longer refers to anything. Every lane ships a worked example that costs nothing. Writing the report needs credits.