I've had a little different experience. Learning from earlier posts I had taken the skeletons on training missions to earlier biomes and leveling blood magic rapidly. Greydwarf spawners and spawners in draugr villages are very good for this. By the time skill level reached 33 I took them on wolf and lox hunts and all they needed from me was keeping the protection bubble active and the archer one-shot drakes and deathsquitos with ease. Then we went into ML and they seemed to enjoy 1-star seekers but soldiers did need some help from my ember staff. I play solo but as others have written you can also protect your mates in coop and get even faster blood magic growth. Also eat 1 health and 2 eitr foods and keep some of the eitr potions with you and of course the full eitr weave set. Also they are good for guarding you as you mine soft tissue and iron in ML since we all know how the locals are drawn to your mining activity.