Jumpers blame the occurrence of twisted steering lines on everything from how they collapsed their canopies to the Coriolis effect. But no matter how they occur, if left unattended, they can lead to problems. It does not take many twists before lines start wearing unevenly.
As the slider grommets slide down the lines during opening and hit high and low spots created by the twists, they create more friction—and therefore more heat—on the high points. This creates a set (sometimes called a memory) in the lines, which causes them to twist up again the next time the jumper lets go of the toggles after landing. Once this set burns into the lines, it is imposable to rectify. In extreme cases, a set can increase the frequency with which canopy pilots experience tension knots that shorten brake lines and cause unwanted turns, poor landings and buffeting when using front risers. As always, maintenance is the best solution. The better a jumper takes care of their gear, the better the gear is going to take care of the jumper.
When you perform your canopy-control check after deploying, spend that extra second or two it takes to check the brake lines and make a mental note if you need to untwist your brake lines after landing or before packing. Better yet, if you have the altitude and no other canopies are near you, spin the toggle a few times and take them out in flight.