See why a running total of parcels delivered is not the same as a delivery...

https://andersonssuperbthoughtss.timeforchangecounselling.com/what-should-i-write-before-doing-any-arithmetic-with-a-real-world-dataset

See why a running total of parcels delivered is not the same as a delivery rate. One counts parcels over a time window; the other measures parcels per hour. A warehouse example shows how units and time windows change what a chart tells you.