Arrivals come from multiple directions (LOMON, FYNER, TRN, STIRA), not just LANAK, so it is too simplistic to assume that arrivals can be spaced and speeded onto the ILS via LANAK.
Arrivals via LANAK for RWY23 are more or less pointing towards final anyway and when RWY05 is in use and traffic permits, direct routeings to centrefix are co-ordinated between Glasgow and Scottish.