This turns a 1 hour task into a 1 day task. Fast feedback cycles are critical to software development.
I don't quite understand how people get into the situation where their work can't fit on their workstation. I've worked on huge projects at huge tech companies, and I could run everything on my workstation. I've worked at startups where the CI situation was passing 5% of the time and required 3 hours to run, that you can now run on your workstation in seconds. What you do is fix the stuff that doesn't fit.
The most insidious source of slowness I've encountered is tests that use test databases set to fsync = on. This severely limits parallelism and speed in a way that's difficult to diagnose; you have plenty of CPU and memory available, but the tests just aren't going very fast. (I don't remember how I stumbled upon this insight. I think I must have straced Postgres and been like "ohhhhhhhhh, of course".)
It's likely you haven't come across these use cases in your professional career, but I assure you its very common. My entire career has only seen projects where you need dozen to hundreds of CPU's in order to have a short feedback loop to verify the system works. I saw this in simple algorithms in automotive, to Advanced Driver Assistance Systems and machine learning applications.
When you are working on a software project that has 1,000 active developers checking in code daily and require a stable system build you need lots of compute.
There's a lot of folks in startups who think 100 devs is a large org and can't comprehend the scale at which '100% tests pass' stops being a build blocker. I've migrated from such an org to a late stage startup and 'tests must pass' even if fifty engineers are blocked with their PRs and the release train is fully halted. 'But our pipelines must be green' no they don't, at least not all of them.
I don't quite understand how people get into the situation where their work can't fit on their workstation. I've worked on huge projects at huge tech companies, and I could run everything on my workstation. I've worked at startups where the CI situation was passing 5% of the time and required 3 hours to run, that you can now run on your workstation in seconds. What you do is fix the stuff that doesn't fit.
The most insidious source of slowness I've encountered is tests that use test databases set to fsync = on. This severely limits parallelism and speed in a way that's difficult to diagnose; you have plenty of CPU and memory available, but the tests just aren't going very fast. (I don't remember how I stumbled upon this insight. I think I must have straced Postgres and been like "ohhhhhhhhh, of course".)