There is no set number of times you should repeat a yoga pose during a workout. It can vary and will depend on how many poses you set out to do. For example, you might pick ten poses and go through them once or maybe twice. Or you could choose only three poses and move fluidly from one to the next, doing multiple sets and multiple reps by starting over with the first pose each time you complete the third one. Also, there are some other determining factors such as physical fitness, age, medical condition, etc., which may dictate the lapse or number of times you can perform yoga.
The same is the case as to how long you should perform each asana. There are no pre-determined standards about the amount of time you need to hold a yoga pose. However, yoga asanas are held anywhere from 1-2 breaths to upwards of 5 minutes, depending on the type and focus of the yoga pose. It is advisable to hold ease pose fr a minimum of one full inhale and exhale, and each breath should be long, slow, and deliberate, making sure to fill your lungs completely before exhaling.