Over-discharging cells can cause gas build up that makes them swell. Research shows that LiPo/LiOn cell failures are usually down to the variability of the chemicals in them, the manufacturing process variables and the materials used. Variations in the thickness of the separators, the slightest burr on the metallic elements, and gas produced due to high current rates causes the cell to swell and change shape. That may activate the fault and cause a problem.
Store them at just above nominal for long periods, more than that for short periods up to three/four weeks. As Neil says, the state of charge after a decent race length is just the ticket, so don't worry about doing anything else unless you are hibernating them for the off-season when discharge to 3.7/3.8v per cell is the best policy. Getting them there at a high discharge current is not necessary, and may cause gassing and swelling that leads to early failure.
Stick to 0.5C as a maximum discharge rate and you'll have cells that last and last. HTH
