Realized I was doing my taxes in the wrong order for a decade

I had a client last March in Des Moines who brought in a shoebox of receipts, and I caught myself hitting the standard deduction before checking if her itemized medical expenses cleared the threshold. Turns out I'd been running every return that way since my second year at the firm, which probably cost a few folks some money over the years. What tipped me off was a software glitch that forced me to recalculate line by line, and suddenly the state credit flipped from zero to $380. Now I always run both scenarios side by side before picking, even when it adds 15 minutes to the file. Has anyone else had that moment where you realize a habit is just a habit, not a method?