yes ok, but

when mana savings mode is on it doesn't rejuvinate at all till the settings threshold is reached, by then it might be time to cast an HT witch doesn't have the 10% cast time reduction
maybe its just difficult to explain, but it feels like healing goes a little better when i manually put rejuvenation on the tanks and melee and keeping the glyph active at all times (but not as a high prio of course), this is when i have mana savings enabled of course, when its off, the glyph is almost always up because i have rejuvenate set to a high threshold
to be clear, keeping rejuvenate up on 3 to 5 melee classes doesn't make me go oom faster, but it does give me a HT for under 1.9 sec witch feels better in the high damage areas
it also makes me feel better to always have a rejuvenate on our monk, couse they are still squishy as hell