Strange since I jailbroke I have checked each day and not seen any detail under general>usage for usage and standby times and yes its been fully charged! Anybody have any thoughts?
its because you have used the respring button. this setting doesnt work to well on jalbroken devices because of that. it loses all data whenever a respring happens.
Just to elaborate on 3cit's answer, the respring clears some cache files. These files include the ones that show the usage data, so whenever you respring, you lose them. A reboot doesn't affect this however, even on jailbroken devices.