After an aquisition earlier this year I got the task of doing an SAP-Integration for the new company, last time I did this 5 years ago it was a 6 month task, but with the experience and skills ive gained since I estimated it would be a 3 month project (with or without AI, most work is just logistics, AI cant help much there).
In those 3 months I was able to not only integrate SAP but also deliver a completely modernised user-facing software for that integration. While I could have written that software myself in a vacuum it would have never been worth it financially, since it would have delayed the launch of the integration by 6+ months. Building the software post-launch of the integration would have easily taken 2.5 years at minimum.
But this is also basically a "spherical cow in a vacuum" scenario, where I was essentially acting as a solo dev, in full operational control of the project, with deep domain knowledge of the topic and an allready fully set up codebase that I knew perfectly while working down ideas I've had in my backlog for 5+ years.