Ben West’s remark in the METR blog post seems to suggest you’re right that the doubling period is shortening:
… there are reasons to think that recent trends in AI are more predictive of future performance than pre-2024 trends. As shown above, when we fit a similar trend to just the 2024 and 2025 data, this shortens the estimate of when AI can complete month-long tasks with 50% reliability by about 2.5 years.
Ben West’s remark in the METR blog post seems to suggest you’re right that the doubling period is shortening: