I worked at a large company where we didn't unit test. We should have. I worked on embedded SW and HW projects for office multi function printers.

Due to poor planning / management, unit tests often weren't done. Bad decisions by others ended up biting me! I got pulled into a project to do a big refactor because somehow I was considered the DSP expert and a predecessor picked a lame DSP for the new version of the product. No unit tests meant I was pretty screwed.