when I'm fishing split shot, I always start a square knot, standing ends in the open split shot, close the knot loop on the outside of the split shot, then pinch the split shot so nothing can slide.
Pinched split shot sliding around is a no-no, it has teeth and even though it's soft metal, it's harder than nylon or fluoro.
E.g., on a fly tippet dropper, I can clip the complex dropper rig complete with split shot, tie a perfection loop to each side of the cut, put the complex rig in a leader wallet, loop it on and fish it again next time.
My largest rainbow, 27" and 8 lbs was caught on a reused 5X (4-lb test) tippet dropper just that way.
Here's that buck on size 22 dropper.
It's ok to let the rubber Otter's Milking egg (soft) and bare hook (no teeth) slide on the leader, but not the split shot. Here's the same rig, same day, smaller rainbow took the Otter's Milking egg (orange), which slid up the leader to the fixed split shot. The small fish is on the sliding bare hook. I put the milking egg on the leader with a quilting needle, slide up the bare hook, tie on tippet, and the tippet knot bump-stops the hook and egg - the split shot is a foot above the rest.
Bottom center just above, you can make out the black and blue size 22 dropper that took the big buck above (such tiny flies make up 70% of the biomass in any tailwater).