Another approach is to limit bags prior to security for domestic flights. This has been done very effectively at HKG (CLK since it opened a decade ago) where only one bag (either luggage or personal-item) is allowed beyond the BP/PP check just prior to immigration. The only exception are F/C pax and elites, who are given a cabin-baggage bag-tag which is collected by the staff who enforce the procedure with near 100% effectiveness. Most planes depart HKG with plenty of stowbin space available.