It is enough to practice a part every day. If you practice twice a day, it is difficult to keep up with nutrition and rest.

Select 4-6 movements for the target muscle group, with 4 groups for each movement. The main strength training movements (such as bench press) can be practiced to 6 groups in the initial stage, with a little more than 20 groups, which can be completed within 45 minutes, shortening the rest time between groups and fully stimulating the muscle groups in a short time, with better results. You said 2-3 hours of exercise is too long. After 2 hours of exercise, muscles provide energy and consume muscles.

My general training cycle is chest, back, shoulders and legs, one day each; Abdomen and waist will be practiced every other day, and 15 minutes will be added after strength exercise. I don't pay much attention to the muscles of the two ends and three heads of the arms and calves. Generally, if I practice, I will practice together after chest and back exercises.

Exercise every day, usually in the afternoon when you are at your best. Practice before going to bed at night, supplement protein after practice, and then sleep and rest, and the effect is also very good.

The elements of fitness are not clear in a few words. Usually in the gym, you can communicate with others and learn from each other, so you need to sum up more by yourself. Come on!