Automating Excel Bulk Replacement with Python and openpyxl: 3 Steps to Reduce 3 Hours of Company Name Changes Across 200 Files to 5 Minutes

The day I fixed "Company XX" 200 times using Ctrl+HLast October, I had to update the templates for quotes and invoices due to a client's company name change. There were just over 200 files to process.

22.4% of AI's 1-file fixes miss their impact—grep doesn't show them. Reducing to 0% with 44 lines of standard library code [Python measurement]

You ask an AI to "just fix this function." The diff comes back clean, and the tests pass. Yet, a few days later, you realize a completely different file is broken—anyone who lets AI touch their code ...