what your instructor should have told you is that you should leave enough distance in front of you to be able to react to any situation.I've never heard that before. In fact my driver's Ed. teacher told me exactly what iPwn said: center lane for more evasive options.
you should not need to swerve at all.
it shouldn't matter if someone brakes, rolls, flips or crap falls of the top of their car, you should have left enough time between your self and the person that you are following to be able to take safe evasive action.
Safe evasive action includes.
slowing down, stopping (emergency braking) slowing and changing lanes, (changing lanes involves checking the other lanes to make sure that you're not cutting people up.)
I'd never want to just outright say that I was a better driver that someone else. but if you don't leave enough space between you and the person in front so that you can respond to emergency situations then that does make you a bad driver!
plan your position in the road. in accordance with the traffic around you, the road surface, the weather conditions. -and yes, sometime that might actually mean using the centre lane, (for example in hard rain when the "slow" lanes was flooded)
failing to plan is planning to fail.
planning to swerve is planning to fail. I'd love to see a big/tall SUV successfully swerve in highway traffic going highway speeds (70MPH in England).
most likely emergency steering, of a top heavy vehicle will lead to a lot of people being late for work and your car laying on it side!