I take the outside of curve to disc sander and just lightly clean up any zigs or zags , then spindle sander to inside curve and do the same, then clamp together and check the glue line, just like a dry run on a bow. Then adjust the inside curve because the disc sander on the outside curve is rarely out of line. Rarely have to do much more than that.
Will not sand the back profile til I'm ready to finish the riser up for bow glueup.