Somewhat off topic but I think this may be relevant. If you look at the history of Western art from the renaissance to the very early 20th century there was a focus on the perfect replication of nature and the ideal form (the ideal form being mostly from Greek sculptures a very narrow period of between 450-400 BC). This is perhaps best illustrated in the Bargue Gerome drawing course from about 1850 that taught students to copy what they saw as accurately and as carefully as possible. At the time this was considered to be the pinnacle of what an artist should aspire to be and to do. But this type of work led to images that, for all their perfection in detail and rendering, lacked life. And so there was a movement away from this type of rote copying as artists attempted to convey the energy or the emotion of their subject. The flip side to this movement away from the established art trends of the time was to gradually lose the skills of being able to accurately copy the subject.
The point is that in order to copy what you see takes a lot of time depending on how accurately you want to do it. But the dogged pursuit of accuracy can lead to lifeless images. To avoid that it's important to also focus on capturing the gesture and the best way to learn to do that is by limiting how much time you have to draw the subject. The artists who strove for perfection would learn to draw from casts so that they could spend as much time as they needed on the subject. Drawing from life was reserved for more advanced students and even then the model would hold a studio pose for many hours for the artists to concentrate on accuracy. Later artists would spend less and less time learning to draw from casts and would instead focus on the gesture or expression of the pose.
So to the question of photos or life? Do both. Photos have the advantage that you can capture much more detail and be as accurate as you like with them where as drawing from life will help you to capture the essence of your subject and will help you build confidence in your line work as you learn to capture a pose in as few strokes as possible. Both have pros and cons and so long as you are aware of the limitations of both then you should be able to benefit from both.
Anyway that's just my opinion.