A. While it is appealing to let winners run by not rebalancing, it is a short-sighted idea. Why?
Because there is always a time when the outperforming asset class to suffer a correction, and you will experience a larger loss due to the larger than originally specified portion of your portfolio.
Plus, there is no one could predict how long the winning asset class will continue the current trend. That's the reason you need a rule-based rebalancing and just follow it, instead of trying to time the market.