1.3 times the stall speed is very much a rule of thumb to be used when you don't have the POH (perhaps because you are certifying the aircraft, or because you are flying it unexpectedly (eg pilot incapacitated)).
Under these circumstances you won't go far wrong with 1.3 x Vs, but if you do have the POH you should follow the guidance in that in preference.
Once you have flown the aircraft a few times you can then nail the approach speed for that particular example. If you are too fast you float, or even balloon, if you are too slow you thump rather than squeak.
There are times when you want to thump predictably (most obviously short fields, but also when there is a risk of aquaplaning...yes, it happens in light aircraft) so you reduce approach speed to that which you have pre-determined in your experiments.
There are other times when grace and artistry are important (on the pull, nervous passenger etc), and runway length isn't a factor, when you might want to go to the upper end of the speed range.
It is important also to think about wind speed, gustiness and cross-wind. You should add speed in strong, gusty winds. In a steady crosswind, if you use the kick-off-drift method, you should adjust down to be certain to touch down preditably, but if you are wise enough to use wing-down this is unnecessary.
Here endeth the diatribe.
W