after being disappointed by my local grocery store brand, I learned that the Wally brand was RO. I've been using it happily ever since in my 18.5 WSM. a full ring w/a full load in a non-weber chimney gives me consistent temps and good longevity. I get multiple cooks out of a full ring just by knocking out the ash and adding a chimney of lit.
that being said, I have yet to christen my 18.5 ots. so I can't comment on how it works in a grill vs smoker.
Beware the wrath of a patient man. 18.5 WSM and "Buddy", my converted Budlight OT grill.