I've done it two or three times now and it makes a difference where in the bag you put the grease. Some in the corners, some in the center and then some more in on top of the bearings. Basically distributing it around the bearing so it pulls in better. When the air is drawn out, the resulting vaccum pulls the grease into the voids. You can kinda help it along too as its sucking the air out. I like it. My DD all the wheel bearings were done this way and no trauma thus far and I got quite a few miles on it already since the axle swap.