I worked in a heavily regulated industry. Everything required a manual test. Let's say you have an employee ID that is 10 digits long which they use to log in. You had to have some else (couldn't be the developer) to write a series of tests, get those tests approved by 5 people(with specific titles) then a third person to execute the test, then the second person had to write a report saying it all passed, then that report had to be approved by the same 5 people.

That typically wasn't the delay. The delay was to execute the tests we needed to stop production. That typically was a 6 week wait(unless urgent for "reasons") and changes like "I will drop scrap by 83%" was typically told wait till July 4th or Christmas breaks. Why? Because production would be down for 3-4 days typically. Someone had to start the system, ok no entry produces error, executor and developer have to sign a physical paper, restart the whole system, now an entry of 1 digit produces an error, sign the form, repeat for all digit quantities up to 9, repeat for all digit quantities up to the choosen value(based on severity if an issue occurred), 2 people sign for each one, system restarted between each. If you had say an enter button and a cancel button each had to be checked for each quantities of digits. Oh but wait what if someone just types there name... Now repeat everything for alphabet values... What if someone does combination, more tests, more restarts, more signing.

Reports easily surpassed 1000 pages, no one really had time to check all that so I saw so many missed signatures and missed tests. I asked the "senior validation expert" can I just automate a lot of these tests using unit tests and attach a computer generated report of all tests passing and the source code of the tests? " the response I got was" what's a unit test? "they still don't use any of them to my knowledge.