Honestly, the question of which timeframe to choose for the RSI indicator doesn't have a universal answer. It all depends on how you trade and what you want to achieve.

If you're a day trader or scalper, you need quick signals. On a 15-minute chart, the RSI indicator will react to every price movement, allowing you to catch short-term opportunities. Some scalpers go even deeper—on 5-minute or even minute charts—but there's more noise and false signals there. Experience and additional filters are required.

For swing traders, an hourly or four-hour chart is the optimal choice. On these charts, the picture is clearer, and genuine trends and pullbacks are visible. You can hold a position for several days without worrying about every jump. The daily chart also works well if you're willing to hold a trade for a week or two.

For long-term investors, it makes sense to look at weekly and monthly charts. There, the RSI indicator shows only serious signals—true trend reversals. Signals are rare but significant.

What to consider when choosing: firstly, how long you usually hold positions. Secondly, whether you're looking for an entry point or trying to understand the overall direction. On smaller timeframes, the indicator is more sensitive but generates more noise. On larger ones, everything is smoothed out, and signals are more reliable.

Practical advice: don't get stuck on a single timeframe. Many successful traders look at several simultaneously. For example, a daily chart to understand the trend, and a 15-minute chart for precise entry. This is called multi-timeframe analysis and is more effective. Start with the timeframes that suit your style, then experiment and find your optimal option.