I have done the overnight thing, too with some of my newer snakes until I learned their feeding habits. Now I don't usually leave mice with them for more than an hour. My male amel is not really interested in food right now, so after 30-45 minutes, if he hasn't eaten, back into the viv he goes and my snow gets the mouse. She has yet to refuse a meal. Ironically enough, she is the most slender of all my snakes.