Sparta has terrible manpower to begin with. To make matters worse, the only units worth a cent in their roster are Homoioi (1st class), their Perioikoi (2nd class) units are slightly above mediocre and their Helot (3rd class) units are downright awful. Does anyone even recruit Helots? Problem is if you don't recruit them, you empty your provinces from the 1st and 2nd class citizenry opening a gateway for an explosive Helot growth, even with buildings that stack 1st and 2nd class population growth bonuses. Anyway to get rid of them damn Helots?
Homoioi 46, Perioikoi 100, Heilotes 73,855!
Perioikoi 2,275, Heilotes 220,689!
The four Helot class units available to Sparta, (Note I am using experimental battle pack by KAM hence the unit stats are different from base game). Heilotes troops are completely useless. And yet, somehow I have to hire them to keep my population balanced, and 50% of my army consisting of arguably the worst units in game. There isn't a single faction in game with such terrible 3rd class units.
P.S. I don't mean any disrespect, but while I understand why Sparta has severe manpower problems at the start of the campaign as is historically accurate, it makes no sense, that they continue to do so, even once they acquire the territorial equivalence of the Roman Empire.