The gap between “done” and received.
Why work gets stuck between one person finishing and the next person starting.
A task can be complete for one person and still be a problem for the next. The email was sent. The stock arrived. The instruction was given. Somewhere after that, the work stopped moving.
Following a handover reveals what a process diagram can miss: who notices the gap, who chases it, and whose memory is keeping the operation together.
A useful question: what does the next person need in order to begin?