Adapt. Yes, you should know that your strategy might not work in all market conditions. So you adapt to the changes that the market develops during various Global or fundamental events. One thing many people fail to do as a trader is that they fail to update their strategy over time and feel more relaxed. The world is evolving and so is the market. You can have a good strategy but still not be profitable because you failed to adapt to different market conditions...
Exactly so many good strategies may not be favourable to different market conditions thus is a more reasons one need to take not of this and make hay while the sun shines. So I key in the aspect of saying when you think your strategy is fluctuating in giving you profitable results do well to update and upgrade it for better performance.
I would say he should upgrade and update, but not for "better" but more about consistency. I rather make 50 dollars per day, than a thousand dollars once a month. So when someone is building a strategy, they should be focusing on how to make money consistently, that would be a lot better.
I believe it would not be all that good or great if they have a system that is very volatile, and very bad at times, because then good times would not be as profitable since most of it or maybe all of it is taken by the bad days. So figure out a way to be consistently profiting, even if small amounts, only focus on the wins, if there are losses, then try to minimize and figure out a way (like stop loss) where you can get out quickly and not lose much money.