It’s easy to talk about SOLID principles, design patterns, testing, moral expectations, self responsibility, and any other guide lines for a better world. Sometimes it’s even easy to adhere to those ideas, to put them in practice, no matter how may times some people repeat “there wasn’t/isn’t time”.
Although, there are situations that really stand against all best practices, like big legacy products which are already on the market, used by many clients, developed by many people who are managed very strict, in order to maintain… order. Or you need to get fast on the market.
The minimum that can be done is isolation. The least you can do is to throw your code in its own corner and use it only from there, then go back to change it whenever you want, without fear, with minimum cost and risk.