It depends, I think. Some settlements are dead-ends and require more effort to maintain (i.e. garrisons) than any strategic or economic value gained. For example, Iuvavum has less than 1000 pop., which means it's going to be ages until you can wring something out of it, and in the meantime you're attacked from all sides by the Dacians, Germans and Gauls.

Or, expanding into Nicomedia from Byzantium as the Macedonians when you're fighting the Greeks and the Brutii is likely to open a front with Pontus and maybe the Seleucids, which may overwhelm you-- better in this case to stop at Byzantium.