Depends on the type and diameter of line and the relationship between the spool diameter and those factors. With braid, you can fill into the bevel at the lip of the spool (I like 1/4 or 1/2 way up). With mono and fluoro (were I ever to spool with fluoro) you want to stop at the bevel, slightly less with larger diameter or stiffer line. For bass fishing, I wouldn't try to squeeze every last yard into the spool, no need, distance isn't usually a factor. For other fishing, particularly from shore or surf, distance can be everything, so it becomes more critical.