Do Learned Magicians' need amulets for longevity?

Salvete Sodales!

Learned Magicians have a SuSa guideline that allows them to improve their living condition modifier up to a maximum of +10. The suggested method is the creation of amulets with at least 4 charges with a duration of season. To produce such an amulet costs a season, and it almost certainly won't help as long as a hermetic longevity ritual. I just wonder whether a different tactic is compatible with the rules:
Chartae (which only take some hours to perform) can have the durations season and moon as well. If a learned magician creates a charta with duration season and some days before it expires creates one with the duration moon and after the passing of the solistice/equinox again creates one with season duration (…), then he should be under the effect for the complete year. This just takes 8 days of a year, but of course increases the risk that – if the magician can't perform his magic in time – the effect is interrupted.

Is there anything wrong with this reasoning? If not, a learned magician who manages to keep to his schedule might grant improved living conditions about five times without loosing seasons. Actually this would even lead to better results as they get the same lab totals for chartae as for amulets and don't have to spend levels on charges. Alternatively by using other targets than individual they can support a lot of people. I can imagine some villages famous for their inhabitants' long lives which are just the product of the local cunning woman's charms.

Just to prevent people from charging me with munchkinism, I posted this question because this just seemed too strong, even so I think it is a result of strictly following the rules. Of course the people will slowly get warped from being under a constant magical effect, and the effect won't be as good as a hermetic specialist's longevity ritual, but still the effect seems pretty impressive. (For example the Learned magician I posted in the characters thread could provide a bonus of up to 7 points to a group of up to 1000 people* – and he might be good, but he is still quite young and in no way specialised.)
By the way, though I haven't studied the Vitkir rules as thoroughly as those for learned magicians, I think they can do similar stuff with the Dagaz Rune.

So, what do you think of this?

Alexios ex Miscellanea

  • lab total: 3(Intelligence)+2(Succurro)+11(Salutem)+4(Artes Liberales)+10(Strong Amulet Magic)+10(nativity horoscope)+4(there will be some kind of shape bonus)+3(Magic aura)=47;
    effect: 15(base effect)+3(group, size incresed by two steps)+3(season)=45

I don't think there is any problem with this, other than the ones you pointed out. Essentially, the Learned Magician has to make sure he's in his lab, in a good aura, with all of his materials on all of those important days or the effects for the entire year are lost. If he's the travelling/adventuring type, this means looking at the calendar a lot and doing a lot of pre-planning. If he's just sitting at home all the time, that's not as much of a problem. If I were the story guide, I'd make sure lots of interesting things happened on one of those important days every couple of years.

I don't see any problem with this, assuming you can identify and convince the leader of the community to carry around the amulet. Again, as a story guide I'd make your life difficult on occasion. I'd make you adventure to figure out who the "leader" of the village was. I'd also ocassionally make that "leader" change. If I were feeling really frisky, I might divide the village into factions and say there are multiple leaders. If I really, really wanted to be a jerk, I'd say the leader was the village priest who shuns you and your blasphemous ways.