Shavasana, that last part of a yoga practice when the student is instructed to REST for anywhere from a few to 15 minutes, can be a great choice.... but it is certainly not the only choice.
Students are often told that shavasana is the most important pose.
In a large general class with many levels of students...perhaps.
Shavasana often acts like a bookend, this is how we end a practice....but there is no reason why we must only have ONE way to end a practice.
Ending a practice with shavasana is a nice ritual.
Rituals are helpful.
Practices are built on rituals.
We practice this breathing technique to wake up.
We add this pose in for his amount of time to calm down.
More of those things in the winter season.
More of that practice to prepare for a long meeting in a cramped chair.
But let's not confuse a ritual with a rule.
There is no rule that requires you to end your practice with shavasana.
Realizing that you are learning ONE way and not THE way is guaranteed to take the pressure off both those that are learning and those that are teaching.
PS: This does not imply you should EVER leave a yoga class early and skip the shavasana if that is what the teacher is teaching. Lordy no. This advice is for your home practice... your personal laboratory where you test, revise, refine. And decide for yourself. Think about it.