Consecutive exercises for the same muscle group in one training session?

When working out to gain muscle, is it smart to work the same group of muscles right after each other, or should I alternate between different muscle groups?

Lets say I have a lower body day at the gym, and I have 6-8 exercises to go through. Would it then be smart to do the quad-focused exercises back to back, and then move on to hamstrings, and then calves? Or is it better to alternate between each muscle group?