During the first couple of years, several applications have been built under the Cymonz platform and each of them was designed by a different designer which led to a massive technical and design debt. Building products fast was an understandable strategy for a startup but, a few years later, when I joined the team, current products were very slow, inconsistent and, to be honest, not really eye-candy. That was the time when the term "design system" was barely mentioned in the community so, naturally, we started to redesign app-by-app over the course of two years.
A lot of things were improved during the redesign phase and most of the old debt was "paid off" but in the long run, I created my own here and there. I just couldn't remember the exact shade of grey I used 8 months ago on a similar page... those kinds of things. It was very easy to get lost while multi-tasking between several applications or projects at once.
The other problem was scalability, every now and then when a new feature was about to be introduced it would require creating a slightly different element or page which lead to inconsistent design, again. When that happens a few issues occur, such as slow prototyping, increased feedback time, repetitive design elements, bloated code, difficult usability, etc.
That wasn't all. In the middle of the redesign phase we finally decided to move to Sketch so all Photoshop files were migrated, which messed up some things, too.
On top of all that, the team members worked on three, sometimes, even four continents, so the communication was very difficult. Nobody took seriously the request to update the border thickness on some "not so important" component. The phrase "an ounce of prevention is worth a pound of cure" had a lot of sense in those situations.