Checking your calcium level is just as important as ammonia, nitrite, nitrate, and pH. Calcium levels that are too low or too high will cause a lot of problems, and will affect other water params if not dealt with. You should always know calcium levels. Without the proper balance of calcium the animals can't grow properly, their organs don't function properly.
I would strongly suggest getting a calcium test kit and finding out where your calcium level is at now, and then would also suggest testing it at least once/month when it is regulated. Calcium, like other levels in the tank, will fluctuate over time. Some things will use up calcium, other things will leech calcium into the water as they break down. I have as of yet to see a marine tank that doesn't need some kind of adjustment to calcium level over a period of time... and I've seen the disasters that can and will hit when it's not properly monitored.
As for the examples you mentioned, like the hanging tank... just because someone does it doesn't make it right. People beat their dogs to train them, is that right? It still happens... and depending on who you talk to, some will tell you that its perfectly fine to do so. Puppy mills keep large dogs in small wire cages their entire lives, simply left to reproduce until they can't anymore, or die... is that right? People do it, and if you talk to the people who run those places, they'll tell you there is nothing wrong with it.
You and I both know better...