If you are tugging and making sure your stitches are tight at the beginning of each needle, then maybe you won't have ladders when you keep knitting... Let me explain what sometimes happens to me.
This definitely isn't always the case, but I know that when I'm knitting socks or anything on dpns, I always make my first couple of stitches tight when I've knit onto a new dpn. But usually for two rows down, give or take, it looks like I can see a bit of ladder. However, as I knit on, there are no ladders except for the two rows below my needle. Even when I pull and tug, there's no ladder. It just looks like there is, maybe because it's so close up to the needle or something. Just as long as I'm making sure my first few stitches are tight and I keep knitting, I don't have ladder problems.