Looping method of adding new yarn to tapestry

What I do is to fold the yarn, which doubles the strands. One piece of yarn becomes two strands. Two becomes 4, etc.. It works best when you have an even number of strands. One end of the bundle has 2 cut strands, the other is the loop. When I get near the end of a looped bundle, I thread the new bundle into the loop. When I come to the end of the cut strands, I splice (or overlap, or tuck in the ends, whatever method you use when changing colors or continuing colors).. If I'm done with a color before I get to the loop, I'll snip the loop and splice. If you​ don't want the "jag", then you'd have to splice unless you get lucky and the loop is at the end/beginning of a pass.