The time to practice erhu depends on your piano practice plan. You can practice for a long time if you have time. Students majoring in string graphics in professional colleges spend more than 10 hours every day. In my spare time, I usually pull 1 hour every day without retrogression, but I make progress after pulling for 2 hours. The longer you pull, the more skilled you are, and basically the more solid you are. As long as you practice properly, you should be able to do more without hurting your hands. However, you need to rest every 1 hour 10 minute. If you feel pain in your left finger or right wrist, you need to stop practicing, find out the reason and correct the wrong practice method, and then practice step by step.
Erhu is a stringed instrument. There are two strings, and the modern erhu has a pure five-degree tuning, which belongs to the high-pitched instrument in the Huqin. Now, according to the required conditions, various places have independently developed different shapes of bowstring instruments such as Gao Hu, Jinghu, Banhu, Erxian and Niujiaoxian. In order to meet the needs of symphonic music in China, according to the erhu system, China Hu was also invented.