Improve what everybody sees and what nobody thinks to inspect.

There is always a visible layer and a hidden one, and it is easy to keep the first presentable while letting the second rot. The hidden layer is where the failures come from, though, since nothing checked regularly tends to break unexpectedly. Working on both is more expensive and it is the only version that holds up over time.

Find one part of your work that nobody inspects and bring it up to the same level as the visible part. It will feel like effort spent on nothing. It is usually the part that decides whether the whole thing lasts.