I take a different approach. I complete only the minimum number of provinces needed to unlock the advanced scouting tech for the next chapter. It is true that my city is much smaller than it might be otherwise because of this. I'm not convinced this hampers my development, however. It requires me to be much more selective about the buildings I place, but this is an advantage going forward as I will consistently be opening up new space as it is needed for additional features. It also means that I never run into the problem of not being able to produce a research needed to negotiate provinces -- the provinces I'm negotiating now still only require tier 1 goods, while I've already unlocked my tier 3 boost. On this timeline, I'll be finishing 220 provinces by the time I enter Sorcerors & Dragons.
This has the advantage of also having plenty of open provinces available for scouting and completing encounters during events. A disadvantage is fewer open provinces for tournaments, but I find I'm generally able to score 1000-1600 points in a tournament, which is decent for a player of my size.