Calcium shouls always be providedd. Where it gets tricky is what is supplied by your soil and its amendments and what do you need to provide through fertilization.
In a soilless/hydro context this is easy.. probably 100-130ppm (elemental ppm) should be maintained in reservoir or in your fertilizer mix -- this assumes proper 10% or more runoff waste water to avoid buildup in a solid substrate vs a reservoir in hydroponics. Soil is a bit more complicated, but that doesn't mean 'worse' by any means. There's just more trial and error invovled due to how much Ca is being released by any amendments included in the soil or added by you. Products vary, so there is no one-size-fits-all answer for soil. Even with soilless there are other variables that can impact exactly what you want for ideal supplementation and avoiding toxicities/deficiencies over time.
pH and other concentrations/ratios of nutes may impact availability (see Mulder's Chart for a visual aid) and therefore need a slightly different concentration of Ca than others. Simply observe and react. If you get deficiencies, you obviously didn't provide enough leading up to those symptoms. If you run into toxicities, and Ca will definitely start to lock other stuff out, you now you over-dosed it leading up to that point. Tracking your weighted average or elemental ppm can make these observations easy to correct with greater confidence and a better educated guess on the adjustment needed.. The longer it takes for an imbalance to form (def or tox), the smaller the adjustment is necessary -- and vice versa for bigger adjustments needed.
It's about the long-haul effect on not just what happens tomorrow or next week. take notes about dose and timing... There may be more fog of war with soil, but the same ends can be reached. Familiarity with your products is just one extra step to consider while working it out. If you buy different soil or amend it differently, then you'll have a new learning curve to get thruogh... same process as above, but at least you have a better starting point by comparison to a completely fresh start.
Some people like simple, watered-down bits they can memorize, others like to understand a bit more of the cause/effect and nuance invovled. Simple fact is more than one local variable can make for fairly large differences of need. Assuming everyone's garden will function exactly the same is doomed to fail at some point, even if it covers 'most' situations. I always appreciated more in-depth answers. Each to their own. If you don't like them, then don't read them, and the person asking the question can simply pick a simpler one. It really doesn't fucking matter, lol. if there is some misinformation or concern, list your concern and provide some evidence as to why. if it's just anecdotal, that is not reliable evidence - all of history has proven that low-success rate, lol.