First of all what is the hotzone? The hotzone is a virtual concept describing the effect of loss of reaction time between two opponents. In this distance the reach of an attack is about equal the reach of a defense, or the reach of a counter attack. However since these distances are equal, the one who responds to an attack is in great disadvantage as he has to first identify the attack and then either move his body away from the danger, or deflect the blow, kick, knife, or stick away from its course of reach to his body.
Therefore even if you get punched in the chin and it is tucked, it will cause enough distraction with opportunity to the opponent to keep hitting you.
Everything can be determined few split seconds before you enter the hotzone and you are lifting your arms incidentally en route using them for attack or defense - before you enter the hotzone! Of course if the strikes are not powerful enough and your tactics suck, then opponents could recuperate and it would have been good if you tucked your chin and you can exchange blows until one of you falls and bla bla blah...
Often in Fighting Sports Sparring and Competition you will see shadow boxing used for defense for moving in and out of the hotzone – In for some action, and out for safety… Once you are in you can continue with a combination if the opponent is still standing or if he evades your first and even second attack.