6 Man mechanics on scrimmage kick

[NJOfficial]

For anyone familiar with 6 man mechanics, the FJ watches the returner man for fc signal and the SJ is supposed to watch the gunners.  Does that mean he watches the gunners on both sides?

[sir55]

FJ is on the Press Box side of the field and has coverage of 2/3 of the field, SJ has 1/3 coverage on his side of the field.  Until the kick reaches the receiver, FJ and SJ are each responsible for gunners in their area of coverage. Once the kick reaches the receiver, the opposite deep official assists with cleanup of players in entire deep field of play.

[NJOfficial]

But the FJ is responsible for watching the returner if he signals for a fair catch, how can he do that and watch the gunner? 

[CalhounLJ]

FJ's have eyes in the back of their heads. Seriously, dancing eyes are the trick. Don't lock in on either area but alternately scan every part of your zone.

[sir55]

It's just a disadvantage of the 6 man mechanics.  We are expected to multitask and just do the best we can while always getting it right.