I recently wrote about reform in Ohio that specifically calls out not splitting up municipalities when possible. How bad is it now? How do my maps fare? So, I wrote an analysis to check. Here's a preliminary result just for Ohio:
Standard Map: 226 places* split (24.1%)
My Map: 330 places split (35.2%)
Is that bad? I'm not sure. I would like to see a distribution of that over the size of the places split. Splitting a town of 4,000 people seems unnecessary, but splitting a city of 1,000,000 is inevitable. This is to be expected, given that the pure-compactness process explicitly does not care about any boundaries and any human process would at least look at that. If an official map broke up more cities, that would have to be the result of some horrific gerrymandering.
Given that I have this data, a future step would be to alter the solver to try not to split cities and towns. I might do a in-depth study of one state, such as Ohio, and see what the tradeoff between compactness and non-splitting is. At the limit would be following the hard rules in the new Ohio law that absolutely does not split unless there is no other way to make equal-population districts.
(*A "place" is Census bureau jargon that includes all kinds of cities, towns, villages, and some other kinds of municipalities. I'm counting the C1-C9 city-like incorporated areas, but not military bases or 'other'.)