I have the Taylor K1766 salt test kit. I got it mostly out of curiosity rather than need.
Like pooldv says, the important thing is that your SWG is happy, and don't have any alarms.
The point is that with salt, it doesn't matter what the test result is, as long as its working all is well.
The strips are more accurate when they're fresh, but still not very reliable by themselves. Even the K1766 is accurate to only a couple or 3 hundred ppm.
What I do, and works well for me, is do nothing unless the low salt alam light comes on, then add a couple of bags at a time until the low salt alarm goes away. Then add another couple of bags for good measure and I'm good. Of course this only works because I check my SWG staus at least every couple of days, which is good practice for everyone.