First, phrasing suggestion (emphasis is my suggestion):
Second, I suspect that the players will get tired of deciding who gets guidance and just say something like, "We decided as a group that Darvinius is just going to cast guidance on Aien Styn once per hour, unless we say otherwise." So the cantrip will turn into a permanent buff for one PC, and probably not the PC who invested spell resources to get it. I may be wrong about that -- you know your players and I don't -- it's just something to watch out for.
This is a good idea thank you.
All, as I said before I don't want this thread to turn into another Guidance debate. All of your points are quite valid, I have in fact voiced them many times in other debates about Guidance's balance. I just feel that in my current new campaign the old arguments don't work as well, and I am simply getting tired of the amount of guidance rolls and guidance reviews I as a DM are having to do for this particular game. So I am trying a new approach, please respect that. I am not here to say that guidance is busted in most games, I believe it is fine most of the time. I am looking at a corner case, and I'm asking you to help me review a houserule for that particular corner case