Back in the day, I was quite heavy into IV coke and oxys. I destroyed all the veins in my hands and arms. There were highly visible dark lines running from wrist to elbow, and half of them nearly to shoulder. All around the arm, 4-5 continuous tracks. Same with the tops of my hands, 7 1" or longer lines on each. With the coke binges, 30+ shots a day wasn't uncommon for me, and the damage meant each of those 50 times was anywhere from 1 to 25+ pokes to find a vein, and new needles were rare (stupid yes, but when a $30 box of 100 lasts <4 days and they're not OTC where you live, it's tough not to go by the 'until the numbers come off' rule). Even my palms have some tracks. Shooting there hurts like a motherfucker, btw. Most of the lines have faded since I quit coke 3.5 years ago, and spent a year in jail. They're faint white lines now. But they're all completely collapsed. I have only one spot left on my body outside the neck and groin, this one miracle spot I can hit on my hand, by going straight down 90 degrees into it, which hasn't collapsed despite 3-10 hits a day in 7 months before jail and the 3 since I got out.
I knew a girl with tracks all over her neck, tho her arms weren't nearly as bad as mine. I told her I thought it was hot. That led to some fun.