We're on similar pages.
First -- the cognitive tunneling effect the OP is concerned with is really a pretty near instinctive level action. When we move to dealing with a threat or crisis -- we focus on the most immediately perceived issue. Hence the "invisible knives" or focus on keeping wings level rather than dealing with a stall; it's what was immediately perceived as the problem, and under severe adrenal stress, it's hard as hell to refocus. It's wired deep and hard, because it was probably not very beneficial to worry about stubbing our toe on a tree root when Mr. Sabretooth Tiger was about to eat us...
You can overcome that sort of wiring -- but there's a price to be paid. Typically, you end up simply trading the old instinctive response for a new one... and that new response might create problems in another setting. (And the training process isn't really enjoyable... visit classical operant conditioning.)
Second -- if you don't maintain an appropriate level of awareness, it quickly becomes dysfunctional. In Condition Yellow, you're alert, accepting that there are potential threats around, but you haven't focused on one. In Condition Orange, you've recognized a potential threat, and are paying attention to see what it's doing. In Condition Red, you've focused 100% on that threat, and are ready to take action to end it. (Those who add Condition Black describe it as panic mode; that's the whole situation we're trying to avoid!) Condition White is all guards down, no expectation of any threat. So... at home, behind locked doors, White is probably OK -- but Red would be seriously inappropriate! For a cop on patrol, Yellow to Orange should be going on routinely, with "dips" into Red. For an average office worker, spending their day in the office, Yellow makes sense, but they probably won't hit Orange very often. And so on...
Taking on an inappropriate level of awareness for the activities and environment leads to problems. The cop who "can't turn it off" and looks at everyone like a suspect isn't exactly fun to be around, right? Neither is that naif who can't see a bad thing happening in the world and needs someone around them to keep them from walking into traffic... Both wear out the folks around them, in different ways.
So the trick is to set yourself at an appropriate level for where you are and what you are doing. I'm currently in my house, with my son and 2 of his friends. Yeah, I'm not on White -- I'm a kind of low Yellow. Like anyone else, I've had days when I don't remember my drive home -- inappropriately on White. At work, I get dispatched to a call, and I'm shifting from Yellow to Orange, focusing on the specific concerns of the call. I might find myself going to Red as I notice a suspicous person whose hands are concealed, and isn't responding appropriately to my words -- then back to Yellow as I see the earphones or realize that he's deaf. Maintaining an appropriate level of awareness means that when you need to shift, it's a conscious change aimed at what's happening, not a sudden "oh crap!" event that leads to jumping from Yellow (or White) to Red (or Black).