Dow Theory is applicable to any stock market, any market trend, and under any circumstances. The reasons are as follows:

1. Stock markets in any country or region invariably use the terms "bull market" and "bear market" (or "long market" and "short market"), which carry the same concepts.

2. Every stock market trend is either a bull market or a bear market without exception, so Dow Theory's concepts influence every investor.

3. Every investor needs to understand whether the current market is a bull or bear market and, if so, which phase it is in. Even for short-term trading, it is essential to grasp Dow Theory's concepts of bull and bear markets.

4. Whether reading newspapers, browsing the internet, or flipping through financial magazines, one will inevitably encounter the terms "bull market" and "bear market." These terms, introduced by Dow Theory, have become a universal language in global markets.

5. Thus, Dow Theory's usage rate arguably surpasses all other stock market theories. Anyone investing in stocks must familiarize themselves with this theory.

6. The essence of Dow Theory has since been found applicable not only to stock markets and their derivative investment instruments but also to any financial market, such as forex, bonds, and gold markets. Today, terms like "bull market" and "bear market" are widely adopted across financial markets, demonstrating Dow Theory's extensive coverage.

The Accuracy and Reliability of Dow Theory  

Regarding the accuracy and reliability of Dow Theory, we can analyze the following:  

1. Since its inception over a century ago, Dow Theory's interpretation of stock markets has always revolved around the concepts of bull and bear markets. History has proven that stock markets indeed exhibit these trends, confirming Dow Theory's fundamental correctness and reliability.

2. Dow Theory further divides bull and bear markets into three phases, each with distinct characteristics. Historical market trends validate this three-phase theory as equally accurate and trustworthy.

3. Occasionally, stock experts may disagree on whether the current market is bullish or bearish or its specific phase. This discrepancy does not reflect flaws in Dow Theory but rather differences in analysts' perspectives—some may analyze correctly while others err. Proper application of Dow Theory with accurate analysis proves its extreme correctness and reliability.

4. This stock market theory has stood the test of time, remaining highly accurate and dependable for over a century.

5. Of course, correctly applying Dow Theory benefits investors. However, merely understanding it does not guarantee accurate market analysis. Misidentifying a bull market as a bear market, or vice versa, can lead to severe consequences. Analytical errors stem from the analyst's skill level, not flaws in Dow Theory itself—just as a martial artist's defeat reflects their lack of mastery, not the art's inadequacy. Dow Theory's accuracy and reliability remain exceptionally high.