Sorry, I think I sort of missed that about the conifer needles. Yes, they do take awhile. So yes and yes.
It is workable to just put compost on top of the soil as a top dressing I do that mid season when the plants need a boost. But I think the compost does more good, gets broken down to feed the plants quicker, when buried. You can just move your mulch out of the way to do that.