I lived for a long time in a town with 32,000 inhabitants, and during rush hour there was an S-Bahn every 15 minutes to the nearest big city...
Shows me that population numbers don’t say much. I come from a town with 35k inhabitants and the experience over the last two decades, in which I’ve been aware of it more consciously, was.... mixed.... As a teenager I still got by bus from my parents’ home to the city center about every hour... then every two... then at some point, apart from school buses, simply nothing ran anymore and on Saturdays there were still 2 call buses a day (fixed schedule model, just corresponding to the normal bus line and woe betide you if you didn’t call at least an hour in advance to “reserve”). Within a few years this had developed from “usable if you plan a little time buffer” to “well, if you wanted to use it, you had to arrange your entire daily schedule around it.” The latter state then persisted with slight variations (sometimes there was one more bus, then again not) for several years. At some point at the lowest point, the public transport provider actually went completely bankrupt and with the takeover by the new one, it seems to have slowly developed back in the other direction. Two years ago I checked once, we were back to about a 2-hour interval. And as of today, there is again an hourly schedule AND most buses now actually stop at the main train station, which previously could only be reached by car (horrible pedestrian connection completely without sidewalks and only individual buses that were not particularly well coordinated with the trains running, both have been VERY significantly improved in recent years. At the all-time low, even the P+R parking was subject to charges, but that was quickly repealed due to protests), so that you can actually get to the nearest big cities again purely by public transport. (With that, you can now get about hourly by RE to the nearest big city, or since there’s also one in the other direction, about every half hour to a big city... you just have to see which one :P) My point was actually just, while you think of a city with 32k inhabitants as having a 15-minute interval to the next big city, I think of 35k inhabitants as having improved a lot already just because of the hourly schedule that has only existed again for less than 2 years ;)