Tunnel vision

Especially in blitz I notice after the game that I often only looked at, say 10-15 squares out of 64. Is there a special way to overcome this stupid habit or should I just consciously try to avoid it and it will gradually go away?

The more you practice looking at everything the more natural it will become.  First step is to play games where you have time to look at everything :)

With only a few minutes on the clock, if you want to play well you should have tunnel vision and only be looking at a few important lines.  If you try to get too fancy, sure you may be winning but you'll likely lose on time in the end.

The more you practice and the more concentration at the time of playing blitz the more winning , the more results ......    .