For me, if it came sealed in a bag, and looks clean, it most likely IS clean. If I'm at all concerned, I run water through it.
I only sanitize any tubing that will come in contact with chilled wort. That's typically a dunk (getting inside matters) in a bucket of Starsan.
I'll soak any tubing I've used that's got something in it that won't rinse out in PBW for as long as I think. Sometimes overnight or for a few days. Just depends on what else I have going on. Once I pull it, I just rinse it completely (again, inside and out) to remove any trace. Then it usually goes into the brewing supply area, or tote, until next brew day.