Hmm... like how? Wayne usually stay in bed, because that way storing is quicker, if he stays up running errands, storing takes time. The state i which he is then, is different. So you can store health passively but it takes a lot of time. If time's of no limit it's fine, if one is a bit unwell.
That's how it happened, we see Sazed in combat for 4 times during 5 years. Pretty much time to store healing, huh?
Though it desn't matter much, as when you have only one ability you build a system around it. When you have all of them, you use favourites