honestly I used to test my water on a regular basis without fail, but, after watching and listening to many other fish keepers I found one constant variable amongst many of them if not almost all.
Why bother with the whole water testing thing because there is actually only one solution to bad water quality so revealed by a test and that is the water change.
So, if the only way to fix bad water quality is to do water changes, why not just do the regular water changes on a total constant regular regime and forgo the tests altogether. And, voila the truth set me free from this foolish thing called water testing which basically is just a whole waste of time on a tank that is well established do the weekly wc and all is well. Yet, skip a few of them and see what happens.
For new tanks yes I will test due to my own personal method that I use to gutload a new tank to super cycle it but after a week or so no need.
As an aside note, when I did do regular testing I always used my nose to smell the water to see if indeed I could use my chef trained olfactory as a guide and low and behold I can actually tell the quality of my water by the way it smells. I also swear by SEACHEM PRIME OR ANY SEACHEM PRODUCTS.
If there seems to be an issue with a tank I do test sometimes but most of the time just pump up the water change regime to double time for a couple of weeks and issues solve themselves out, but thankfully issues dont really happen much with my tanks.
Though I did do a strong battery of testing on the museum set up I took over as per the curator's request to have it documented and man that water was randy, but, as I said earlier constant water changes in the range of 50% totally brought the tank back to where it was suppose to be. So the conlusion of the matter for me is be like sam the toucan and follow your nose and don't get so familiar with your tank that you let contempt take shape in the skip a water change here or there move. Do the water change regularly and consistantly and no probs.
FISH KEEPING IS NOT FOR LAZY PEOPLE, CAUSE LAZY PEOPLE KILL THEIR FISH.