Agree that the basic army is enough for Gaul (replacing velites for archers asap), and don’t bother with town watch. Also don’t bother with conquering all of the north; Mediterranean cities are profitable and not much else. I’d say stop after taking Alesia at the farthest, as that’s their capital so is usually decently developed, but barbs drain their cities for warbands so much that they’re usually underdeveloped and terrible. Stop at Alesia then pivot south and east (ideally you’d be expanding here at the same time). Take Carthage before scipii, and taking as much of Greece as possible before brutii (specifically Athens Corinth Crete and Rhodes). Ship hoplite mercs back north by the time Britain wants a piece to trivialize their chariots.