Appreciate the response guys.
For additional information, the phone is not her primary phone.
It's used principally to receive Line messages from her staff at her tour counter business confirming each sale and sale details. Seldom used for voice calling and cetainly never used for such battery intensive actions such as streaming videos etc.
That's why it's so annoying that the battery runs down so quickly.
After setting "Background usage limits" at "Put to sleep" the battery is depleting at 7% per hour, as verified by the the battery staus saying "A full charge will last about 14h 11m"
My own secondary phone, the same model, says "A full charge will last about 4d 4h".
That massive disparity suggests to me that something is running in the backgroung seriously depleting the battery.
Having accessed "Developer mode" and being able to see all apps and services running, I don't know how to identify which app/s are doing the serious depleting.