In Rival magic when talking about the possible breakthroughs from the integration of virgillian magic (p74) it says "Hermetic magic currently lacks a way of binding a watching effect and a spell together without a ritual.
I've always ruled (well since fifth edition came out) that watching ward is a ritual because it creates a "Spell container" of indefinite duration. I'd be fine with a duration moon watching ward being non-ritual. In fact the patient spell from magi of Hermes p113 can be seen from a certain point of view as a duration concentration watching ward (at least that's the guideline that was used for it). Do you think that this is a conflict with the Rival magic take on it?
I had also thought that Watching Ward was a ritual due to the Duration of "Special". The relevant guideline makes no mention of the fact that such a spell has to be a ritual. So, I don't see why in RAW a "spell container" of other durations (Sun, Concentration, Diameter, Moon) need to be rituals.
I think it makes sense, because otherwise, you could have watching ward of concentration duration for high level + maintening the demanding spell for moon = watching ward really long without any need of vis... and you just have to cast it back.
With a moon duration maintaining the demanding spell you could have really long duration creations, really long duration healing spells, and spells in general that have durations longer than year without any rituals. I don't think that the watching ward use is good grounds for taking a position against short duration non-ritual watching wards. (it might be a reason to take a position against a moon duration maintaining the demanding spell).
Even with a spell, as it is written in the RAW (or at least, as I understand the way it works), if you cast while relaxed, nothing stops you from stockpiling non-ritual watching wards effects cast at the limit of your ability, potentially with the same trigger.
This also lessens the use of Watching Ward: A magus can trap his sanctum with spells, renewed each moon by casting without stress. So maybe the author wanted to go against that.
I think this is too bad, because, IMO, the ability to stock some effects, especially ritually sponted effects, in a limited duration watching ward, is awesome and reminiscent of a long tradition of magical characters (From Merlin in the Amber Chronicles to the Dying Earth wizards) and would have loved to do it for a few spells.