The Only time you use a spindle roughing gauge is on spindle blanks,IE:grain running from headstock to tailstock and the outside of an endgrain bowl,STRESS the outside,as this has the same direction as a spindle,but never ever on the inside,if used on cross grain/sidegrain,the tool can be bent/broken and you really can lose fingers and thumbs,its bad enough having a major dig with a skew on spindlework,but I think you have to be pretty foolish to use a spindle roughing gauge on the inside/outside of a crossgrain bowl,Regards,
Eric.