I don't think the game is playable RAW since it's not precise enough in its language.
Then I think we fundamentally disagree on the nature and purpose of the rules.
That is how I have ruled, but it leads to the cantrip being applied more than feels good.
Then change the spell. Limit it. Change it to +1d2 or +1. Change it so it can't affect the same person doing the task more than once. Change it so that it can't be cast on the same cast more than once every 10 minutes. The rules exist as a framework for the game. The framework should support your campaign. The same rules that define the spell explicitly empower you to change and alter them as you see fit. Make the rules create the framework you want to support. You win no prizes for following the rules as written. Figure out what goal you want to achieve with your change, and then change it. But if it's "I don't want them to use
guidance all the time" then you should probably just ban it. If for no other reason than wasting table time every time someone does something.
Look, it's one thing to come to the Internet and say, "Is this too good? I think we're having a problem," and to seek feedback and discussion from others. But it's only useful if you act on it. If you're not going to act on it, then it's not the game's problem anymore. No, I'm not saying "the game isn't broken because you can house rule it," I'm saying, "identifying a rule as needing to change for your table and choosing not to change it is your fault, not the game's."
Here's my take on
guidance:
Personally, I have found that reminding players that it's a touch spell, and that it's got verbal and somatic components and therefore is just as obvious as casting any spell is enough. It's is a significant disincentive in a dungeon or social setting. Most NPCs find characters randomly casting spells deeply concerning and moderately aggressive, just like the players do. (What kind of honorable person needs magic in a conversation, after all?) Furthermore, I never put skill checks in place that the players aren't allowed to overcome (supposed to overcome, even). If I don't want the players to overcome something, I don't let them roll at all. Why would I let you roll if I know you can't get past something? So it doesn't bother me all that much if they overcome skill tests. They're not meant to really be that challenging anyways. At the end of the day, anything that
guidance works on wasn't a big deal in the first place. It was put there for the players to get past. If the players succeed because they remember what's on their character sheet and they work together,
for God's sake let them. That's the whole point.
More and more as I run the game, I don't allow rerolls of most skills. The first die roll determines the outcome. That means the players get one roll. If they succeed, then they pass. If they fail, then it didn't work and the players should move on. If they fail, and the adventure
requires them to succeed, then they still will pass but something unfortunate happens or the process involves additional difficulties. Either way, they get one roll. That one roll is enough to create the equitable uncertainty required for the game to progress. I don't need 10 die rolls as an exercise in random number generation. That's just a waste of time.
Finally, make players describe what they're doing before letting them roll the die. For knowledge checks it's obviously not possible, but the reality is that this is the most difficult part of making skill checks. Yes, great, god is helping you. What are you doing? How are you going to do it? What is your approach? How long are you going to try? I still need to know all that. Anybody can roll high on a d20. The difficulty and challenge of the game shouldn't be about that except when it has to be (i.e., attack rolls). So don't make the players feel like they're getting a major bonus by rolling an extra +1d4.
Besides, mathematically, the spell only does something meaningful roughly 12% of the time.
I think that the creature the cantrip is cast on, and not the caster, decides what check to apply it to. For example - rogue "can I have guidance to help, um, search for secret doors", cleric "sure", rogue sotto voce "I add the d4 to my sleight of hand, pick pockets check".
Simply put -- and this was the point of the way I wrote the narrative in
this post -- the narrative doesn't have to directly follow the game mechanics. Close enough is good enough. Remember, "character" choices are really
player choices. The game just says "character" because continually saying "the player or DM in control of the character" is cumbersome. The narrative doesn't need to include a conscious choice by the
character. That choice can easily be considered as an event of the game and not the narrative. The player makes the choice. The character accepts their fate.
