One of the favourite spells in my campaign is "Purification of the Festering Wounds" CrCo20. A month long +9 to Recovery rolls for injuries and diseases is huge.
I have had to remind our Healer mage not to recast it on a character month after month lest the character gets Warping from continuous mystical effect.
However, the question comes up, what happens if it is cast on an old mage with a LP during the winter months? Since we check for Aging Crisis in winter, the idea seems to be just in-case the old mage suffers an Aging Crisis, they have a +9 to recover.
PS If a mage with Enduring Magic casts "Purification of the Festering Wounds", would a duration multiplier of 7 or greater cause the recipient Warping from continuous mystical effect?
Recovering from an aging crisis does not involve any recovery rolls - or any other rolls for that matter. So any bonuses to recover would be irrelevant.
If you survive the aging crisis it takes a season to recover. Period. (If you have the Unaging virtue you can probably skip the recovery period entirely.)
If you are under the influence of a Longevity Ritual you will automatically survive an aging crisis, but the ritual will cease to function after that, so you will need a new LR.
Any mystical effect that is active for half the year or more will cause warping as a continous mystical effect.
Bonuses to recovery rolls are nice, but remember that for a Heavy wound you roll once per season to recover, and any bonus needs to be active for the whole period to be of any use.