With mobile operating systems like iOS one problem you frequently encounter is the user moving from one physical connection layer to another, ie WiFi to Cellular and back. iOS will send requests on both, but won’t move your existing request from one to another.
So for one app I write the user (say a company executive who always complained his photo uploads failed but was too busy to give a detailed bug report or even a specific time it happened) would take pictures at home or office, which starts uploads on WiFi, then put the phone in their pocket and get into their car and drive away. So I ended up using relatively short timeouts (30 seconds) and automated retries.
So for one app I write the user (say a company executive who always complained his photo uploads failed but was too busy to give a detailed bug report or even a specific time it happened) would take pictures at home or office, which starts uploads on WiFi, then put the phone in their pocket and get into their car and drive away. So I ended up using relatively short timeouts (30 seconds) and automated retries.