Deflection or disruption is the key to countering as is making them miss totally too.

Like Adam said in different words: blocking is a whole one count wasted.

Thats why to block and counter can be done if you deflect and counter thats the reason i said you could catch one close to your chin with your rear glove while launching your jab simultaniously :

Im not by any means saying fight with it up there the whole time thats not good I agree with Chris's comment there.
But to be relaxed enough to pop that rear hand up sometimes to not stop but check the ending of a hit gets you into the timing to be able to follow it back home as well.