Plan for the day the machine stops
Branch reception is usually designed on the assumption that the self-service machines are working. On the day one is not, that demand lands at the counter and the design fails. A threshold that prompts extra desks to open is a small piece of configuration with a large effect.
Why people pile up in a branch
A long queue almost never means the branch is short of staff. It means two-minute transactions and twenty-minute ones are sharing a single line, or that a self-service machine stopped working and its demand moved to the counter. Splitting the flows by transaction type and measuring each separately usually cuts the wait before a single extra person has to be hired. It is one of the questions branches ask us most often: why are there so many people waiting.
Three months later is when it matters
Any system looks well run the week it goes live. The test is three months on, after staff have changed and exceptions have crept in. Reviews scheduled into the contract are what keeps the configuration matching the branch.