Which one?

As a data point, my first tech job was QA for a COBOL compiler vendor. They supported roughly 600 permutations of architecture, operating system, and OS version with a byte-coded runtime and compiler written in C. I maintained a test runner and suite with many thousands of tests, ranging from unit tests to things like Expect UI tests. This was considered routine in the compiler vendor field, and in the scientific computing space I moved into. I worked with someone who independently reproduced the famous Pentium FDIV bug figuring out why their tests failed, which surprised no one because that was just expected engineering.

Then you had the other end of the industry where there was, say, 50k lines of Visual Basic desktop app where they didn’t even use version control software. At a later job, I briefly encountered a legacy system which had 30 years of that where they had the same routine copied in half a dozen places, modified slightly because when the author had fixed a bug they weren’t sure if it would break something else so they just created a copy and updated just the module they were working on.