The simplest thing that could possibly work

More senior devs on my team follow this principle with passion. After seeing it applied for a bit it started to remind me a lot of mathematical simplification exercises I did in school (Gosh, I never thought I'd end up using the concept). It works like this: If you see duplication - remove it; if a class is too light on functionality - merge it with another relevant class. To think of it, it makes perfect sense as when a code base that is rid of duplication and unnecessary complexity there are less places we'd have to go to change it.