METR Time Horizon 2.0—The benchmark you’ve been waiting for

Published on July 8, 2026 11:41 PM GMTTL;DR: I applied METR's time-horizon methodology to Microsoft Excel. On my 23-task suite, Excel completes tasks that take an unaided human 6.5 hours at 80% reliability — more than double Claude Mythos Preview, the best frontier model on the current METR plot (~3 hours at 80%). Excel's 50%-time horizon is 54 working weeks. I have updated my probability of spreadsheet-induced catastrophe by 2035 from 0.1% to 5–10%. Then I wrote down everything wrong with my me...