If you are busy swinging a sword at the ogre right in front of you, I think that probably counts as hyper-focused. You need to roll to see the beholder when there's a whole lot of other stuff you're busy doing.
I had to fight everybody in my dojo to get my blackbelt. Then I had to fight several of them at once (all brown and above), including a fellow blackbelt candidate on my side.
It ain't hyper-focussed. It's seeing the entire field. I actually feel it as unfocussing, widening my vision, so I can see my entire enemy, and the rest of the field, so I can position him. It's the difference where a white belt looks at the spot he's going to hit you. An advanced student does not.
I think sniping would be more prone to hyper-focus (not paying attention to periphery) than sword fighting. Zooming in on one target, versus moving around and maneuvering the other guy.
Might be worth talking to larpers and martial artists. To see how often they get "surprised" by enemy combatants who should have been obvious.
Note, this is all different than tha bad guy who is trying to come up from behind (where you obviously can't see).
The scenario you're testing for is can a person in a fight/exploring a dungeon miss seeing an obvious threat (the gorilla in the basketball game).
I guarrantee you, the basketball players all saw the gorilla. They were not hyperfocused on the ball, they were focussed on the entire field, because they had to know where they were, the enemy was, and where their allies were.