Yep makes perfect sense, if you can maintain those parameters that would be really good although its not written in stone its probably a good idea nonetheless to avoid any problems.
Just keep testing for another while and soon enough you will be able to do away with the test kits, just bear in mind though as you add and subtract from the plant biomass that the uptake rate will change, for instance if you remove fast growing plants and replace them with slower growing plants this will change the balance, and obviously if you added lots of fast growing plants they in turn would require more nutrients, but normally if the tank is left alone and you are happy with the setup, the nutrient uptake remains pretty much the same.
You are making very fast progress just dont forget about the co2 (sorry i had to throw that in couldnt be all good)
Just keep testing for another while and soon enough you will be able to do away with the test kits, just bear in mind though as you add and subtract from the plant biomass that the uptake rate will change, for instance if you remove fast growing plants and replace them with slower growing plants this will change the balance, and obviously if you added lots of fast growing plants they in turn would require more nutrients, but normally if the tank is left alone and you are happy with the setup, the nutrient uptake remains pretty much the same.
You are making very fast progress just dont forget about the co2 (sorry i had to throw that in couldnt be all good)