I should add that when you use this technique of trying all three simple settings algorithms at once, there is a potentially confusing side effect: when you have three sets of the same resolution differing only by timing, OSX only shows you the resolution once. If you select it, you don't really know which one you're getting. SRX tells you which ones failed OSX's checks, but in my case, two passed at each resolution. In the case of 1368x768, one was decidedly better in practice than the other - one was not possible to fine-tune perfectly; it was always too wide by about 20 pixels, which meant it was getting scaled, and therefore not a dot-by-dot representation of the mac's intended display image.
A better procedure would be to try one simple-settings formula at a time, reboot, see if you like what it produced, and if not, delete it, and try the next one. It's certainly fine to do it with both 1360 and 1368 at once b/c you can tell those apart in the display pref pane. So it would take at most 3 reboots to pin down the best timings for each of those resolutions.