Melt Pool and Burn Time
A soy candle is different in that it develops a "memory" each time it's burned. I wick my candles to melt all the way across when given sufficient time. The wax melts about 1 hour per inch of diameter, so it takes nearly 3 hours to get a full melt pool with my 50-hr jar.
Like in the picture, the melt pool will be about a centimeter deep. This will give you a full 50 to 60 hours of total burn time and the best scent throw. The smell comes from the molten wax rather than the flame! If the candle doesn't have a chance to melt fully across each time, it will tunnel afterward. The flame will gutter due to inadequate oxygen and you won't get much time out of it.
Limit maximum burn time for any candle to 4 hours.
Burn within sight, on a stable, heat-resistant surface.
Keep away from drafts and flammable materials.
Keep away from children and pets.