I'll be honest, a proper concerted effort to stretch tends to be saved for classes where I'm made to, and moments in front of the TV when I feel guilty for being lazy. Normally after being in the gym, at training sessions, or going for a run, the last thing I want to do is spend 15 minutes stretching off - if it's not been a straight dance session I'm not the best at making myself commit to it. Hitting the showers always seems so much more appealing. Today, seized by a moment of out of character good sense, I came in from a run and actually made a concerted effort to stretch and have made a subsequent decision to push myself back into good habits.
(Note: a couple of plies and shouldering your leg in front of the mirror does not constitute stretching properly).
Normally I'm lecturing people about how much a waste of time stretching classes are, how dancers are increasing their chance of injury by obsessing over increasing their flexibility to levels their bodies aren't happy going to. I stick by that. 85% of your flexibility is down to skeletal joint factors. If you've been working towards the box splits for 6 months and aren't getting anywhere - it's probably because your hip joints weren't built to move that way. No amount of stretching is going to change that. The remainder of your flexibility is down to muscular factors (10%) and environmental factors such as the studio temperature or your stress levels (5%). So hours spent stretching are going to improve your flexibility levels by a grand total of 10%, and you probably reached that level halfway through your first year of training.
So why am I advocating stretching after every workout session? Because it will maintain and prolong your flexibility. As we get older our muscle fibres lose their elasticity, you've been losing it since your teens. When we're 30, our muscles are significantly less elastic than they were when we were 18. This is exacerbated by trauma our muscles sustain through training. Stretching after a workout allows your muscle fibres that have bunched and torn through exercise to realign themselves along the length of the muscle; if your muscle fibres heal while bunched up, the length of the muscle fibre is shortened and your range of motion is compromised.
If you leave them like this 5 days a week, 52 weeks a year for 10 or more years, your flexibility will be dramatically decreased, stretching will be painful, and spending an hour stretching once a week will do nothing for you. Short, regular stretching sessions done after every class, rehearsal or workout is going to allow you to maintain what you've already got. If you're training regularly, if you've been dancing for years, you're unlikely to gain flexibility over and above what you already have. The box splits might just not happen for you. Ever. You will however be able to keep the range of motion that you already have, and maintain your muscle health by throwing in just a few minutes after each session. Which is also a hell of a lot less boring than spending a 60 minute session trying to inch your leg up an extra couple of degrees.