@ElfGunn
If you want to keep it as cheap as possible stay within the 30 cleared per chapter guideline. Start scouting as soon as you enter the chapter and hold off clearing until you have a few useful upgrades on the tech tree. In my opinion staying within the chapter guidelines is only useful in the lowest chapters (1-5ish). They should stay really close to the chest guidelines. It is best for them to also hold off clearing until they have unlocked a few useful upgrades (production increases, Squad Size increases or troop upgrades) It is cheaper for them that way.
And players under chapter 8 need to know that if you clear in perfect rings you will hit the orc wall at province 222 iirc it is ring 11 . It is barely possible to break through if you fight and use troop boosting buildings. It is impossible if you cater. You need orcs so stay off the orc wall until you are in orcs or ready to enter orcs.
Other than those exceptions, it is best, imo, if you overscout to your cities maximum ability while still meeting your other demands. The number of provinces cleared is a metric in important future productions(seeds) and in pretty ancient wonders(Dragon Abby).
So keeping it cheap will cost you mana and seeds later.