I think it also depends on genetics. Frankie's sire and dam are both large. His sire is a good deal larger than Cole. Frankie's paws are already larger than Cole's. And Cole's no tiny thing...although he's not huge either. He's about 28.5" at the withers...or close to 29". I've seen larger.
I also limit their calcium to around 1.2 to 1.4 per day. BUT the key is the calcium/phosphorus ratio. If you throw that off, you'll be asking for problems. Keeping it around 1:1 is probably best from what I've read.
The only time I gave any sort of calcium is when he went down in his pasterns a bit during teething. I fed raw chicken backs for a meal a day, or added a can of sardines or yogurt to his food. That helped, I think. He came back up fairly quickly after I started adding those items. The Vet said to make sure it was a food based calcium (free calcium), not a supplement pill and not Tums. (Although I had never heard of adding Tums, apparently he knows of breeders that do. He said the problem there is that Tums bind calcium and then you throw off the phosphorus ratios, which can cause major issues.)