I liked this idea when it came out, and there was some software that implemented it. Mr Schedule by Andrew Pietschy added outliner functionality to Joel's idea, so you could see how much time a group of subtasks would take (and if you should maybe drop that feature group to make your deadline). It had some keyboard driven shortcuts that made it faster to move around in than Excel, while making things simpler.

Unfortunately Mr Schedule and the pietschy.com website disappeared. I made my own recreation using REALbasic / Xojo at the time, but never released it and faded from using it.

Joel Spolsky expanded the idea later with Evidence Based Scheduling:

https://www.joelonsoftware.com/2007/10/26/evidence-based-sch...

That takes the estimates from Painless Software Schedules, but runs a Monte Carlo simulation using your estimates & data on actual time taken, to create a confidence distribution curve graph of when you'll be finished.

Was wondering how StockOverflow guy was doing these days and it turns out he sold the company for $2B in 2021. What's the saying? Time in the market vs timing the market. Good for him but imagine being one of the investors.