I don't believe in under handling, they're not like dogs that thrive on attention. With the snakes, I think the less attention they get the happier they would be.
Over handling is possible, but it depends on the snake. My first corn was happy to hang out with me in my hoodie for 5+ hours a day. My boa would be happy to do the same. However, some of my corns will tolerate the handling for a few hours, but some of them start to show signs of stress (heavy breathing, really trying to get away) after only a few minutes of handling. Most of the time, if they are just trying to get away, I'll handle them until they calm down to just a normal slither. But if they seem stressed, maybe changed eating habits, etc, then I opt for short handling sessions, maybe only two or three minutes once a week.