FWIW, I personally do not think it's a good idea to combine alk and calcium standards into one solution because of issues of potential precipitation after manufacture
I'll defer that to the manufactures or experts. I can only reply based on how "I" use the product as it is "sold" over the counter and their recommendations.
As an aside I did talk to Jim about the Trident calibration and he mentioned he wished they didn't limit it to 8 hours but he respected their choice. Honestly it isn't a big deal use it once for calibration then reference if you store it properly. Rotate out after a few months.
We have bigger issues to deal with.

