A boxing/sparring match and a fight fall into two different fighting areas.
In a set match -- whether it's light contact, full contact, NHB, whatever -- the goal is to learn how to win. You're going up against an opponent in a controlled environment. The hesitation you see is (a) beginners saying, "you go first" "no, you go first"; or (b) opponents at all levels resting/pacing themselves since rounds can last several minutes.
In a real fight, the goal is to win. Period. If you can achieve that in one punch, well good on ya. If "chain punching" works, great. Hesitating and waiting for the other guy to move first is risky at best. Move in, strike, counter, and keep it up until the guy goes down or runs away, but don't give him time to think about his next move. A real fight may only last a couple of seconds, and it probably won't go for more than 30 seconds.
There is a great streak of violence in every human being. If it is not channeled and understood, it will break out in war or in madness. ~Sam Peckinpah