Depending on the type of turn, sitting down might even be your best option. There's this one particular turn on one of my trails which is an unhill hairpin, riding over smooth, flat rocks (See picture below.) As you will see from the picture, there is a fair bit of dust. Due to this, there is very little traction offered on the rocks, yet you still need to get power down to get up the hill! If you stand up, there's simply not enough weight over the rear wheel to keep it planted. Once you lose traction and put the foot down, game over. So I've found that if I keep my bum planted on the saddle, it keeps the weight down, allowing for more traction, which in turn allows me to put a bit more power down, and get through.
So here's a pic of my buddy attacking it.
