I think someone already answered you about this. The answer is yes. The 5th wave can end before 4. If it does this, then it is a truncated 5th wave.This is what you see many times in a double top or double bottom. But in order for it to be a valid truncated 5th wave, that 5th wave still maintain all the characteristics of an impulse wave....meaning that it must still have 5 subwaves.