A key concept in understanding my position (per a few posts upthread) is that a "skill check" isn't a task.I don't see anything in the rules which indicates that. If I start building a wall and halfway through 3 master builders show up to give me guidance, my wall is going to be better than if I did it alone. That far through it might only be +1 or +2, rather than the +3 or +4 if they had been present the entire time, but it will be better quality. I see the spell as similar. It gives a bit of a push, so it doesn't matter if it is to an instant skill check or a longer durational one.