I do a similar thing. Sort of. My Seraphon and Stormcast armies are power armies and my Fyreslayer army is going to be one when it's built (only because I love the Fyreslayers too much to not have them be powerhouses and my Stormcast were the army I really experimented with and used to learn all my tactics) but my Skaven Eshin army is for fun casual games, as will be my Undead Bretonnians, Ghouls, Chaos Dwarfs, Malignants, Gitmob, and Savage Orc armies once I make them. I'm undecided on how powerful I'll make my Cult of Valkia, probably strong enough to be competitive but not as powerful as I could make them.