The sibling post gives a good account of the 90:90 challenge. The last part of any semi-difficult project nearly always takes much longer than the officially d

The sibling post gives a good account of the 90:90 challenge. The last part of any semi-difficult project nearly always takes much longer than the officially difficult “main problem” to solve. It leads to the last 10% of the deliverables costing at least 90% of the total effort for the project (not the planned amount; the total ad calculated after completion, if that ever occurs) This seems to endlessly surprise people in tech, but also many other semi-professional project domains (home renovations are a classic)