This is a very good question. This is the change Airbus made from old QRH which said if flaps jammed at zero select clean configuration. Normal operating speeds(MAX SPEED= 250 KTS). The problem is the elevator is trimmed for Vapp but to retract slats(flaps are jammed) you will have to increase speed. When you moved the lever to position3 it was merely procedural as the slats have the same position for 2 and 3 so the lever can be put to 3. But from 2 to 1 and 1 to zero you will have to reverse the procedure VFE -5 and retract. Closest to Vapp will be VLS for flaps zero since VLS is always correct for the configuration.