When I had mononucleosis about 50 years ago, I wound up in the hospital for 8 days. They drew blood often.
One day, a young nurse came in made an attempt at drawing my blood. I was 6'1' and weighed about 160-165 pounds because I had been sick for several days. I'm saying this to show that my veins weren't hidden under layers of fat. They were visible. Anyway, nurse #1 tries and fails and leaves the room. In a few minutes, nurse #1 returns, and fails at a second attempt to hit a vein, but she did poke the needle in what felt like the same hole. Nurse #1 leaves, not to be seen again.
Nurse #2 enters the room a few minutes later, and she looks old enough to be nurse #1's grandmother. I start to feel a little more positive, imagining she probably drew blood out of Abraham Lincoln or at least Woodrow Wilson, and thousands since. So, nurse #2 inserts the needle into what feels like the same dry hole that nurse #1 hit twice. By this time, I am hurting pretty bad in the left arm on the inside of the elbow. So, I get out of my bed, grab the rolling stand beside my bed and head for the nurses' station to complain, and tell them to please send someone who could draw my blood because I was sick and getting really tired of this crap.
A few minutes pass, and a man who was the head of the lab comes to the room, pops the needle in my arm, draws the blood and leaves. I am feeling really sore in the left arm, but very relieved that it's over. Unfortunately, it wasn't over. An hour or so later, the man from the lab walks back in the room, and says "you aren't going to believe this, but they dropped your sample and broke it." He poked me for the 5th time in a couple of hours in or near the same spot, hit the vein and left. It was over. I have had blood taken several times, both before and since, and that is the only time that anybody had a problem. My arm was very sore and painful for about 2 months afterward.