Better naming conventions, stricter change management, a Center of Excellence with a nice slide deck, enforce the rules hard enough and the Org stays clean on its own.
Fifteen years in, I can tell you this is wrong.
Walk into any office at 6pm and you'll find a cleanup crew. Not because the people there are careless, but because real work under real deadlines always leaves residue no policy prevents. A dropped wrapper. A cable routed wrong because the meeting started in two minutes.
Your Org works the same way. No matter how good your Governance is, there's always a pile of "others": the Field for a deal that closed eighteen months ago, the Permission Set built for one person's edge case, the Flow that was supposed to be temporary. Every one of these was reasonable in the moment. None of them get cleaned up by a policy, because policies govern intent, not the aftermath of a hundred small decisions made under pressure.
Nobody expects an office to stop producing mess once the rules are clear enough. Why do we expect it from an Org?
You can govern the rate the pile grows. You can't govern it to zero. The only thing that works is accepting the pile exists and implement the cleanup to work through it, continuously, as normal operation, not a sprint you get to after the "real work."
Book a free 60-minute Salesforce Technical Debt Audit: a score for Usability and Build Quality, and your top cleanup priorities.