Picking a scab doesn't make it heal faster and in fact when you pick a scab on a wound it makes the wound take longer to heal and could cause an infection of the wound.
The scab is there to help the wound stay protected and heal up and the wound will be fully healed once the scab has fallen off on it's own.
When you have a closed wound you can put some Vaseline on the wound to help prevent a scab from forming and it will also protect the wound from infection.