I am facing this weird issue with my iPhone 4 which is jailbroken on iOS 5.1.1. Although I have to admit I never noticed this before so do not know from when this is occurring. This is what happens.. 1. I charge my iPhone 4 till 100% and then remove the plug. This also resets the standby and usage time. 2. I check after few hours and see that both the times are same. 3. I reboot the phone and when I check after few hours(phone idle or very very less used), the usage time is just a bit changed but the standby time is more which is an ideal scenario. 4. I keep phone for recharging and charge till 100% and the cycle starts from step 1. I am unable to understand what the problem here is and how come a reboot always fixes this.