“Which particular roads would you say are overclassified here?”

I am not saying a particular road is overclassified. I’m saying you’re promoting roads haphazardly and inconsistently, resulting in a loss of information. Local consistency is more important than getting a random selection of streets right by a personal impression. I’ll try to give you some context because I hope you’ll at least stick around long enough to finish the job. In fairness, changeset 148744892 turned out better, so I’m struggling to understand what went wrong here.

In Ohio, by design, state-maintained roads numbered under 100 generally run along principal arterial roads, although some segments of these routes have been bypassed. Three-digit state routes are supposed to be less important, but this system has fallen apart in the Cincinnati area because ODOT ran out of two-digit numbers. U.S. 42 and U.S. 22 are obvious primary roads. (They would even be trunk roads, but they’ve been bypassed by the Interstates.)

Butler, central Hamilton, and western Warren counties have laid out a grid of collector streets along section lines. In the remaining areas, the counties have laid out collector streets in more haphazard fashion, often naming each street after its endpoints. These county roads are generally useful for travel across a township, but not across the county.

However, a select few county roads are maintained as crosstown connections, such as Tylersville, Fields Ertel, East Kemper (east of Montgomery), and Glendale Milford (ditto). Similarly, Reed Hartman is a high-capacity traffic reliever for I-71. These arterial roads need to be classified higher than collector streets, but lower than the state-maintained intercity roads.

It makes sense to classify these crosstown roads similarly to the three-digit state routes, which have a similarly sized service area. Note that service area does not always correspond to length. Lebanon/Columbia may appear to form a “crosstown” connection between Loveland and Mason, but that’s a relatively unimportant connection.

I have just described three classification values lower than trunk. You can decide what to call these three values, and then help me update https://wiki.openstreetmap.org/wiki/Ohio/Map_features#Road_classifications