SWIFT LOOP would be an amazing tool if it worked consistently, which it does not. Many times I'm directly hovering the cursor on an edge and it just doesn't detect it. I will have to zoom out or try an odd angle for SL to finally detect the edge and draw the preview edge loop.
Another key feature that is missing, is (when working with OPEN polygon strips) the ability to snap the preview edge-loop to a vertex that resides outside of the mesh in question. This is how it should work:
1) you place the cursor on the desired edge, the new edge loop preview appears
2) you drag the cursor outside of the mesh, the preview edge loop is now locked but it can still be dragged by moving the cursor
3) the cursor can snap to vertices, allowing to perfectly align the new edge loop to a point (and thus another edge loop)
Currently the only workaround for this that I know of is the following:
1) swift loop draw a new edge loop
2) select the new loop
3) lock selection
3) move tool
4) activate constrain to edge
5) activate snap
6) enable axis constraints
7) choose correct axis
😎 slide edge until it snaps to desired vertex
9) unlock selection
10) disable axis constraints
11) disable constrain to edge
All this wouldn't be necessary if snapping compatibility was added to SL (Cinema 4D already has this and works perfectly)