1% risk per trade is only part of the consideration necessary. If the stop distance is 1% or more of the total pip value of the pair, then a sudden illiquid move will not completely wipe the account out. But a 1% risk position with a 10 pip stop on a pair at 1.0800 would wipe the account out completely on a move half the size as the Jan 15th swiss move. The solution is a maximum position size per pair or said another way: a minimum stop distance.
One easy method: Risk 1% per trade with a minimum stop distance of 2% of the total pip value of the pair.
A trader following that rule in a swiss pair on Jan 15 would have seen about a 10% change in his account size per swiss pair he traded.
What is a 2% of total pip value stop? If the pair is trading at 1.0800 it has a total value of 10,800 pips. 2% of 10,800 is 216. The minimum stop distance for a pair at 1.0800 at a 2% minimum is 216 pips.