I tend to keep my tank regularly nearly topped up, in about 80% most of the time and still DPS a fair deal. Reason I don't keep them totally full is that various tank self heals that at least my usual tank uses regularly would go to waste. Why I keep them that high though, if I heal the same amount anyway it doesn't much matter in which order I do it. CS change when properly weaved between spells is instant so variating between heals and damage spells seem to be, at least to me, just as effective as chaining one type and then other.