Lol!! Ymmv --> your mileage may vary.

I need to clarify that I am not 100% WO. I do use a no-poo cleanser about once a week (have been able to stretch that longer the last couple of times) and WO in between. My hair looks better on days I WO wash than days I use the cleanser.

So you can definitely do WO in between cleansers. Some people do WO with nothing else with success, too. My biggest problem with being purely WO is that the cleansing comes from the friction of really using your fingertips and I don't care to expend the time or energy. Therefore, eventually I experience build-up. When I use a cleanser though I still use very, very little.

As far as cones...since they are usually not water soluble, they would build up but if you were using a shampoo regularly that removes them, then that probably wouldn't be a problem.

Good luck!!
remember, with all advice or suggestions for your hair, YMMV!!
My hair:
2b wavy, medium texture, low porosity, med-high density. Protein finicky.
My routine:
Cleansing: DCNP, every 4-5 days (occasionally use CJ cleansers).
RO: CJSC, occasionally use JCDC
Gel: KCCC, CJCIAB for 2nd day hair (sometimes third)

Heat is my friend: warm water rinses, steam caps, and diffuse dry. I love CLU cloths and my Denman.