Question: How often have there been events that cause a sudden 10%- 20% drop

As the question above ask. How often do we see these 10%- 20% drops?

I just started investing last summer the first day of June and so far in my investing career I’ve noticed a couple events such as the Crowd strike incident, DeepSeek for the AI sector and now these tariffs / administration. My window is small so all this could just be just my luck of when I first entered.

Saying that I’ve seen these opportunities and I’m curious if I should just set aside cash to drop when they happen every so often or just continue learning and practice good investment strategies.

For context I’m in my early 20’s. Primarily in stocks rn, but looking to broaden into ETF’s and index’s.

Thank you!