As has been said already deadshorting from 5.4 volts will destroy your packs, in fact you wouldn't even have to solder the wire on as the voltage would arc weld it for you. Dead shorting MUST ALwAYS be done from ZERO VOLTS and all cells must be equal.
I discharge packs at 20amps down to 5.4 volts and leave them there. I get good performance out of my packs this way along with good life. Rody is a team-mate of mine who takes his cells down to zero and has more punch than me (and better packs
) each to their own, do whatever your comfortable with.