Can you run a 7018 kind of like a cellulosic rod?

Did a 3G vertical up v groove 60 degree included angle on 1/2 inch mild steel with backing today with 3/32 7018 about 100 amps. Looked good and I kind of ran it like a 6010. Up about a centimeter down .5 centimeter and up a centimeter all the way up groove. Beads where about a centimeter. Ran it really hot because of motion. Showed instructor and he wanted me to do more of a weave at like 85 amps. Couldn't really get an answer about why I can't do that. Cut it open and grinded it smooth and couldn't tell where base metal started and weld or bevel started and no trapped slag that I saw. Does it trap slag? Or make it less sound? Can do the weave but this way was easier and faster. Anybody know why you can't do the motion I described?