The worst I've had to deal with was a triple trunk Hawthorn. They send out sprouts almost as bad as a Bradford Pear.
By the time I got done with the Hawthorn, I looked like I had been in a fight with a family of bobcats.
I used the "half of a 55 gallon drum, charcoal" method to scorch the earth where it had been and still ended up with flats on two of my lawnmower tires from the thorns that got left behind.
,...nasty trees.
