I finally hit a 4 foot span on stair stringers without a single wobble on a Chicago job
My old boss in 2019 told me I'd never get comfortable past a 3 foot span, so last week I cut and set nine stringers for a guy's back deck in Berwyn and every tread sat dead flat on the first try, which made me wonder if anyone else here has a span rule they won't break or if I'm being too cautious.
Your old boss probably told you the same thing about driving too, and look how that turned out. Four feet is fine, just don't let the inspector hear you brag about it.