Generic learning points …
Business performance over time (sales and earnings) depends on the resources we have.
Resources are won and lost over time (customers = sum of all customers ever won, minus all ever lost).
Specific to this microworld …
Need for balance between growth of ‘demand-side’ resources (savers) and ‘supply-side’ resources (the service staff who provide the capacity to deal with the workload from savers).
Lead-time required to bringing resources into balance (the hiring and training time). Intangible resources (reputation) can severely constrain growth of tangible resources (savers) – it responds quickly to poor service, and slowly to improvements.
Service demand is driven by three distinct forces – the winning of new customers (new savers have to be processed), the ongoing support for having the customer-base resource (regular account statements and enquiries) and the losing of customers (processing accounts for savers who leave).