Yes, spins can be deadly and should be treated with respect. I never went beyond two turns with my students, as it doesn't teach you anything new or more useful other than sometimes you need to hold the recovery longer to get it to stop. The problem is when it is fully into the spin bad things can and have happened. You will learn what it feels like when the plane is in the right (really wrong) situation to spin, what it feels like to actually enter into the spin, and how to automatically make the correct inputs to recover (or even better, prevent the spin) without going past one or two rotations. I personally think spin entry and recovery, as well as full stall maneuvers, are a vital part of primary training, but should never be taken lightly.