If production code already works (conforms to requirements and is deemed fast enough for end users...which makes it stable) and does not have code coverage, leave it be until the opportunity presents itself to add code coverage and change the code (System Under Test) at will, or a bug occurs related to that code, or it is deemed not performant enough at a later date. ☝🏽
If production code has code coverage and conforms to requirements but could be better and you have time to improve it, proceed to refactor it. The tests will serve as feedback.
Otherwise, it's business as usual (work life balance all the things). Try to allocate sufficient time to add test coverage for new requirements as you’re writing new code but be aware of the scope of the project and when it ideally needs to ship to production. From there’s it’s a balancing act. I’m a natural born ♎️ so I’m innately capable of conducting this balance of a daily basis ⚖️. All hail Egypt 🇪🇬. My African and European heritage have served me well (let freedom ring...U.S.A.!!!).
Deeper than rap - Rick Ross of Miami, FL
To be a bit more concise, wait until one of the following conditions is met/satisfied prior to introducing deltas for stable production code that lacks test coverage:
Put simply, don’t get too cute (yes...you’re absolutely trolling to some degree..instant cringe if it costs your company or team 🏡 ⚖️ 📆 ♋️ 🍑 🚴🏾 at a later date ...but certainly not the end of the world ☀️ ) and code change just for the sake of doing so (you’re exposing unnecessary risk and you have far better things to do w/ your time as an IT Professional - LinkedIn Rocks 🎸). 🙏 🤝 📧 👩🏻💻 👨🏻💻 ⚖️