Calcium and Magnesium Stability - Is it as Important as Alkalinity Stability?

So I know that everyone stresses to keep Alkalinity as Stable as possible for Chalices and SPS.



I have heard one person even say that you must keep it within 1 tenth of one point or your Corals will Suffer (So if your Alkalinity is 7.3 you must always keep it between 7.2 and 7.4 - No Less not More).



But I have never heard anybody say this about the other big two things to test for (Calcium and Magnesium).



I just always here keep your Calcium around 450 and Magnesium around 1350



But I have never heard anybody say you must keep it within X amount of points or your Corals will Suffer like I constantly read with Alkalinity?



So my question is do you have to worry about Stability with Calcium and Magnesium?



For instance if my Calcium was 450 today, then 430, then 490, then 410 the day after that does it matter as long as it is over 400?



Or do I need the Calcium to always be a Constant 450?