If he had a serious heart condition, always one day away from a disabling or fatal heart attack would you say the same, that you couldn't deal with his always being one day away?
90/90 doesn't come from AA...as said above, it started in rehab with professional therapists. It's purpose was twofold. First was to give a newbie constant exposure to folks that had long term sobriety so they would believe it was possible. At first, coming out of treatment, folks tend to be wishful...perhaps even hopeful...but the constant exposure reinforces that it IS possible.
The second reason rehabs started 90/90 was based on the psych knowledge that the only way to form a habit is to do it over and over...90/90 forms the habit of going to meetings.
Where I live 90/90 is easy. I could hit 14 meetings a week within a 20 min drive, and that is morning and evening Mon thru Sat, morning, noon, and evening on Thur, and only Sun being the one day with only evening.
But what about the A that lives way out in the boonies with 1-2 meetings available? Or the A that that lives in one of the few places where meetings are not available? Does it mean that not being to get to a meeting regularily dooms the A to failure? No...it means they must develop another plan.
BubbaBob