Most missed promises come from a part, not from the workload. Order date, expected delivery and the job it belongs to, held together, show which bike can actually move today.
Status is the whole customer relationship here: received, diagnosed, waiting for parts, ready. Visible to the owner, it removes the daily call that interrupts the bench.
The bike is the record, not the customer. Held by frame number, the second service takes half as long and the shop knows what was fitted last time.