I'd like to thanks the person who asked about turnover. I did more back tests on different rebalance period. The optimal period is 6 weeks. The corresponding annualized return is 23.39%, and average turnover (every 6 weeks) is 36.20%. Nonetheless, there is no big difference from rebalancing every week to every 8 weeks. The annualized return starts to drop for periods longer than 8 weeks. The longest period I've tested is 1 year and the annualized return dropped to 14.91%, with turnover (every 1 year) at 75.50%.