The amount of blood is not much... these samplers they are getting, I had 23 taken in the same day at some point and the say after I was fresh as a rose and went to play basketball (I am not a good player but indeed) with friends and I didn'T feel dizzy or tired in any way. 23 samplers in one day is more or less 300-350 ml, not even half of what they take when you go for a blood donation. These little collecting they are having can't downplay their performances, especially as they are taken at a few days of interval, which gives more than enough time to the body to refill the machine.
the USADA test is for the moment the most advanced and most reliable on the market, we'll probably have better in the future but this is far far better than the Nevada or California athletics commission tests if you want to make a full screening.