How did Amazon get away without using a delay?
It’s easy to move the cursor from Amazon’s main dropdown to its submenus. You won’t run into the bootstrap bug. They get away with this by detecting the direction of the cursor’s path.
This is a comprehensive look at usability - relevant three years after it was written.
Criteria for optimal web design (designing for usability)
"The Effects of Line Length on Children and Adults’Online Reading Performance"