That 30x math simply comes from spending 5min typing a prompt, and getting code generated that would take a human 2.5hrs to write. This means in the future most of a developer's time will be spent reviewing code, rather than typing it. Because AI will also be able to write the test cases too, so that effort [mostly] vanishes as well.
Unless your job is producing disposable software (e.g. single-use mobile games for short marketing campaigns), this comment suggests you don't know how to do your job. If a piece of the program takes 5 minutes to describe, but 2½ hours to write, you're spending your time in the wrong place, producing code that's legacy almost on day 1. Quoth https://quoteinvestigator.com/2014/03/29/sharp-axe/:
> The text presents to the wood cutter the alternative either to spend time in sharpening his axe, or expend his strength in using a dull one. Which shall he do? Wisdom is profitable to direct.
Sure, you don't need to sharpen your axe. Given a powerful internal combustion engine, you could drive a tank through the forest and fell many trees in rapid succession. But this strategy doesn't leave you with quality lumber, and leaves a huge mess for whoever comes after you (which may be your future self), and one day there won't be any trees left.
If your job is producing disposable software, be aware that you're using unpaid labour to do so. Some of the programmers who produced that AI's training data are struggling to eat and keep a roof over their heads. Act accordingly.
The 5min example is like a maximum/extreme case, yes. My average time spent writing each prompt is probably 30 seconds or less, and coding time saved per prompt like 25 to 60 minutes.
When I do spend minutes (not seconds) writing prompts, it's because I'm actually typing a "Context File" which describes with full clarity certain aspects of my architecture that are relevant to an Agent task set. This context file might have constraints and rules I want the Agent to follow; so I type it once and reference it from like 10 to 20 prompts perhaps. I also keep the prompt files as an archive for the future, so I can always go back and see what my original thoughts were. Also the context files help me do system documentation later.