Yin Yoga is a gentle and grounding practice that works on the fascia in the body instead of the muscles fibres like Yang forms of Yoga. So what is fascia...it is the transportation system of the body that goes through every other part of the body...it literally touches EVERYTHING inside your body! When using a Yin practice it is import to remember that rest is needed for the body to adjust to what has just happened to it!!!
So what has just happened to it in a Yin practice...? You have opened and stretched the fascia (essentially you have just OPENED the inside of your body!)...this is where we store all our deepest trauma and held emotions! So when practicing Yin these held traumas are being released...this is traumatic for both our body and our emotions...luckily for us, our bodies don't allow us to do it all in one go and only lets us release what we can withstand to feel...that's the reason we cant stretch past a certain point (the body is reflective of the soul and emotions!).
We don't push the body in Yin we only allow it to release on its own terms, by allowing it time (hence the longer holds of asanas) and allow gravity to work on the body..its used to that!! Plus...Fascia work continues to work for about 48 hours after doing the initial work so continued release for the next two days... This is why if you have done a Yin practice you might feel a little 'wobbly' on the emotional front for a few days! This also means that the body needs longer to adjust so pushing to do a Yin practice everyday is very hard on the body and doing a practice every three days is plenty enough if you are looking to heal and release any held trauma in the body...but don't forget to give yourself time to really 'feel' those feels as well...the more we allow them, the more we can release them and move on!