With a little practice the efficiency to straighten strings is quite surprising. Since about 20 years I have been using a setting-off tool that I made especially to do this job, which I am very proud of, simply because well straightened strings give a great finish to a quality string job.
To do a good job with the awl the racquet needs to be still mounted in the cradle, once out of the machine it is quite difficult to straighten the strings, so it's a one-off application.
With the String Thing it is possible to straighten the strings anywhere, anytime in a few seconds and that is a definite advantage.
Since returning to my workshop in Paris I have been using the ST every time I string a racquet and have definitively replaced my usual setting-off awl, there is no way back once you acquire the technique of the ST.
Just to see the limits of this thing, each time I recuperate a racquet to be restrung when the strings are still intact, I try to straighten the strings with the ST. So far it works perfectly on every type of string (monos, multis, hybrids and even natural gut) no matter how badly they are notched, all you need to do is to push the string in the direction needed to straighten the string in the same movement of up and down along the string that you are straightening.
My only problem with this thing is that now straightening strings has become easy to accomplish by any stringer and/or player, which does take away a small part of the value of my string jobs, only because anyone else can do it just as well as I can . . .
I suggest that at least after each time you play tennis, you should straighten your strings and in match do straighten your strings regularly because the racquet will give more consistent results when the strings are correctly aligned.
When straightening your strings I have found it is best to begin with the crosses first followed by the mains. Following this sequence produces the easiest and most consistent results.