The 5F chart is too short. In fact, the bollinger band is the deviation degree of the 20-moving average. Generally speaking, after you get from the middle track to the middle track, you will call back two or three K lines to try the middle track. If you don't break it, you will do it for a long time. Short is the opposite. Note that you can't touch the corresponding upper and lower rails before trying to recover, otherwise it is often not a trend relay, but a turning point. Finally, the 5F chart is too short, generally above 30F, and this trend is often one day, which is very useful for intraday trading, both at home and abroad.

Also, it is very problematic to simply look at the bollinger Band. Only when the trend direction is right can it be useful to look at the bollinger Band.