I don't want to jailbreak so this is a case where I curse Apple's restrictions because if they would just provide some official APIs to control the radios then there would probably be at least 10 different apps in the app store to automatically put the phone into airplane mode on a fixed time schedule. Even 5 years ago my Windows Mobile phone could do that, and it could look in my calendar for when I was on a flight and do the same, it could detect meetings and switch to silent, and it could set my WiFi on or off depending on my location.
I also like the idea of an app that can only let calls through from certain numbers during nightime hours but I suspect that is also prevented on non-jailbroken phones by missing Apple official APIs.
I leave my phone on all the time because I'm very unlikely to be called in the middle of the night. The only time I switch it to airplane mode at night is if I'm in a different timezone where someone might call me during UK daytime hours and wake me in the middle of the night (e.g. if I'm in the USA).
I never switch my iPhone 4 off entirely. With the phone and location services enabled 24/7 but WiFi, Bluetooth and all push and automatic fetch services off, I often get 10 days between charges. My record is just over 13 days and that was still with some light useage. I suspect that if I charged my phone and then sat it on a desk and never activated the screen then I would probably get 14 or 15 days standby before the battery died (of course how I could tell if it was still alive without waking it up now and then is another matter). Sitting there just listening to the network consumes a really tiny amount of power.
- Julian