I think that one's pretty straightforward -- if you mend something with one stitch when it has just started to tear/ unravel, then you save the nine more stitches you'd need to make if you leave it for too long.
Think of say the seam of a glove, at the wrist, that's coming unstitched -- if you get it when there is just one stitch that's come out, you're done. If you wait, then it'll keep popping out stitches until you have to do more stitches to fix it.
Um, as for the next one.... I gotta think a bit. (If my explanation is rejected then I'm off the hook.)