Hi Copper,
I'm sure you'll get lots of different replies, but this is my perspective on it :)
When I feel drawn to use symbols during a treatment then I use them, sometimes I just don't feel the need at all. In the beginning I always used the symbols to focus my intention to begin Reiki. But as Reiki has become part of me, I now use them as tools ie if i feel that an area needs a boost of energy then I might use the CKR over that area or SHK for an emotional matter.
I still use the symbols for my distant work, I find they help me to focus my intention to begin sending Reiki and assist me in mindfulness.
Hope this helps
Gentle Blessings
Helen