police officer friend tells me that driving overly-cautiously is a good sign the driver is intoxicated. Most officers, he says, would stop the driver to check. It's also a sign that a wellness check is needed. This sounds reasonable to me.
Yes I knew a cop retired guy that trained met officers in advanced driving skills etc long time officer said absolutely over cautious driving is a dead giveaway...but he means really over cautious, like doing 55 on a motorway etc.
It Depends where you’re driving, though, on a motorway or dual carriageway any competent driver should be doing exactly on the speed limit to drive safely but in a residential area driving cautiously at 20 or 30 mph depending is the decent thing to do. It’s actually illegal in London now in many places to drive over 20.