Ya man that's how I jelqed for about a year and a half. I never used to put pressure on the sides on my dick (which works the CS). Maybe that is why I really haven't gained as much depth as width.
I only used to put pressure on the top and bottom of the penis. The reason I did this is someone on Thunders, I think, saying that doing it top/bottom worked length more and side/side worked girth more. Personally, I feel that side/side works better for girth. I'm hoping to get some really good depth, as this is how I try to jelq now, although it's much easier to jelq top/bottom than side/side.