Same in Britain, but we don't need runway separation, the departing aircraft only needs to be airborne when the arriving aircraft crosses the beginning of the runway (whatever that is).
5 nm works out at about 2 minuntes. It is recognised that the arrival spacing may reduce slightly in the final stages of approach - it normally wouldn't make more than 1/2 nm difference in extremis and the time difference is unlikely to change much.
UK AIC makes interesting reading - honest!
Eurocontrol are looking at re-categarising their recommended standards
here