The Game Is Over
Honestly at that point - i'd just make it a +1 skill aura as long as a cleric with the cantrip was within 30 ft of you.
Which if someone really has problems with it applying to nearly every check would probably be the best way to fix it.
It's already a +1d4 bonus to nearly all skills for the OP. Lowering that down to a +1 solves his cricism that it boosts checks to high. Making it reliable and no booking at that point hurts nothing for him.
I never thought i'd see the day when a +1 to all checks was stated as being too powerful. I mean what the what?
Well, your suggestion of a simple +1 to every skill check to (assuming...) allies within 30 removes the touch restriction and removes the action requirement since you're making it passive. There is no longer a concentration requirement until it is used as well, freeing up the caster to use a second concentration spell while the party still benefits from the +1 bonus.
So, as I said, it makes it even more powerful in some ways, and despite the simplicity in bookkeeping, is nothing I would want. If the OP wants it, that is great for them.
Now, if,you had said something like:
You can choose one target within 30 feet of you and grant the target a +1 bonus to ability checks. If you and the target are more than 30 feet apart, the target loses this bonus. You can have only one target selected at a time.
THAT would have been a more reasonable suggestion without making the feature even more effective (in some ways) than Guidance already is.