Volunteer mapping can be an addictive thing and I will have to admit that I am probably the wrong person to chime in here as I have been contributing to OSM for over 15 years. And, for what it is worth, I live in and almost all of my mapping has been in North America.
You state that maybe you “just got unlucky with my city” and you are thinking about adding some addresses. Go for it! You will help yourself and you will be helping others!
There is definitely a network effect: If the area is reasonably well covered for road and address data then more people will use OSM. And more people using OSM will lead to more things being added or corrected.
If your city is poorly covered by OSM it likely means that there are few or perhaps even no local OSM contributors in your area. Where I live things are getting pretty well mapped but that is not how it aways was. Even just a single individual contributing to OSM can have a big impact.
For example, when I move to my current city about 10 years ago there was almost nothing in OSM for the area. I made a point of walking all the streets within a few miles of my house verifying street names, noting speed limits, collecting address data, etc. I achieved several things: I learned my new home town. I got much needed exercise. And I made OSM very usable for finding addresses and to a lesser extent finding other points of interest. I notice now that more people use OSM based apps in my area and are adding and updating businesses as the change.
I did this “old school” by walking the area which took be about six months. Nowadays government generated address data is more available and you can “armchair map” to get addresses in. You do have to verify that the data is properly licensed for inclusion in OSM and that varies from state to state in the US. Fortunately, many states are not contributing to the National Address Database (NAD) which is public domain. If your state is a contributor, you have a head start. Even if your state does not contribute to NAD, the data might be appropriately licensed anyway so it is worth checking your county’s GIS department to see what they have and what the license is.
One thing you might miss by importing data from a government database rather than walking the streets and looking at things: Locations of automated license plate readers. Turns out that the Deflock project is using OSM for the data store and contributing to OSM.
You might even find, as many have, that volunteer mapping can be an addictive hobby.
Here is the weird thing as far as I am concerned, I still contribute to OSM but I don’t actually use it that much. A while back I read that the spacial memory and abilities of people who habitually use navigation apps atrophy. Thinking about it, I realized I personally had lost some of the navigation abilities that I took for granted before I got a smart phone (or a car with built in navigation). So I have made a conscious decision to simply look at a map before I leave to figure out a route and possibly some alternative route options then I do not reference a map or navigation app while driving. I certainly am better at knowing where things are at than I was a year ago and I have a better “feel” for when and where I might be delayed by normal traffic. Yes, I don’t know where there are backups due to a collision. But I still seem to get to where I want to go and get there at the time I wanted to be there.