Sometimes I might install new machine heads on a guitar, or do some pickup work, then re-string and take the guitar to my local guitar tech for a fret dress/setup etc. I don't like to waste a set of Ernie Ball's or D'Addario's, since he usually replaces the strings. These are perfect for that situation. I can string up with these and it hasn't cost as much as a more higher end set.
Other than that, they'll get you by in a pinch, but they won't hold tuning or stay as fresh as the higher end strings.