I'm of a mixed vote in including expertise with the EP / wicked edge and belt grinder. I do believe that even for dedicated freehanders that there is knowledge to be gained from using these devices - even if one chooses not to use them for one's customers or for your own personal sharpening. By the same token one who only uses these devices is limited by not freehanding if he only uses a belt grinder or EP or WE - or other adjustable angle devices. In the same way the use of paper wheels is something that would be useful to have skill doing, but I don't have this knowledge and this is very far down on my list of things to learn. As I also don't make my own knives or create my own steel from basic elements, do differential heat treating and have an advanced metallurgy degree, etc, so I feel I still have much to learn.
BTW, can you pick out your stones if they are unlabelled? Can you pick them out by touch (and smell) alone? If this is just a handful of stones, this should be easy. If it's well over 100 stones, now it becomes a challenge. Using your sense of touch, smell, ability to sense shapes and sizes means you are 'becoming one' with your stones
You are allowed to wet the stone to help pick them out, assuming you can find the water blindfolded