The simple answer is "yes" as you know.

It doesn't usually matter, but the more complex answer is that all the stuff that gets grounded should have just one path to the jack. More than one path can lead to something called a "ground loop." That can cause hum too, I think, although i don't think I have ever had a problem with one. My grounding problems have been simpler...either I forgot to ground something, or I grounded something I should not have ;-)