On the spot, if I think the way DH is handling things is reasonable but not what I would do, I let it go. If I think it’s totally unreasonable and it needs to be addressed immediately, I pull him aside and talk to him and we discuss. So far we have always been able to work something out.
As far as big-picture matters when we are discussing parenting and we aren’t with your kids, if we disagree, we go to google and sort of figure it out.