This is not especially surprising. It's not that I can't focus. I can, for hours and hours and hours on end. The difficulty is directing that focus productively. High stress environments provide the necessary motivation, forcing my focus onto the thing demanding that attention more strongly than the usual cacophony of distractions. But high stress also leads to burnout; I can't sustain that for months on end, so I have to cope in other ways most of the time. (Typically by altering my environment to reduce distractions.)