On the street sure, skip gears at low engine speeds. Hell even leave it in neutral coming to stop lights. But at high engine RPM's only the next gear in sequence has syncro's that prevent you from crunching the gear. If you skip gear you bypass the effect of the syncronizers and you can severely damage your transmission this way. Thats why when you drive an old car with bad syncro's you grind gears all the time(unless you double clutch like a truck).