One way

At the end of each Z pass, a retract in rapid until the safe plane is done

Zig Zag Cycle

At the end of each Z pass, a plunge in machining feed rate is done directly on the next Z passe.

Zig Zag Slope Cycle

At the end of each Z pass, a retract in slope in machining feed rate is done to reach the begining of the next Z pass.