Being a slacker who likes to take things easy, I have been using the small chainring to pedal all this while. One other reason why I've been using the small ring is because the acceleration is much faster. Sure beats cranking hard and trying to pick up speed at the traffic light, especially if there is a slight upslope.
Since I had to ride to AMK MRT yesterday, which is a total distance of 8km for a return trip, I decided to use the big ring all the way. Well, it was faster, but much more tiring. Looks like I have to train more to get used to it.