He probably doesn't use his phone as heavily as us which explains the long standby time versus usage time.

Anyhow, I wonder why would ppl always wait till their battery is flat before charging? It wastes a cycle of the battery life.

okay. I just got my 3Gs last week so still a noob. Forgive me if I asked stupid question.
2 days back, I charged my Iphone to 100% and go to sleep at 1.30am, woke up at 8.20 realize battery drop 20%, left 80%. The next day I charge it to 100% at night, wake up found out left 96%, sweet huh. The next day I try again, 100% full charged overnight, next day wake up left 80%.
My question here is, how does set up the phone as new phone affect the battery usage? Done some reading online, some claims JB will drain battery faster especially Winterboard. I am sure that I didnt turn on wifi,bluetooth,push notification, and other stuff cz I double check using SBsettings. The only thing I enable is 3G cz i dun like to use back GSM while I am using Iphone "3G" just my own preference for this.

Anybody can advice? Thanks

Are you sure?
i have a 3GS for a week now, firmware 3.1 non-JB and all my setting are off (push,fetch,wifi,bt and etc), and my Aussie Telco only have 3G reception but will roam to non-3G telco automatically if no 3G reception.
100% charged at night, 8 hours standby 98% left in the morning.
You might want to put it in airplane mode when you sleep to isolate and investigate your problem.
Btw GPS really drain the battery, i went for a 20 mins walk to try out the GPS function to my supermarket, 8% gone. Really hardcore battery eater GPS+3G+Screen On+Compass orientation.