I've also struggled with that part
@MMMi
I want to try to stay within the range suggested, but then if you start to show a deficiency (Cal for example) and supplement for it, all of a sudden your base becomes much hotter. Then what are you supposed to do with the regular nutes? Do the same and now you are at 1.8EC, risking potential lockout due to salt build up? Or should you reduce the nutes, and risk now causing a deficiency by not providing enough of the other nutrients?
It's a balancing act and I've yet to have a grow with no deficiencies, and nice green, healthy leaves all the way to harvest. That being said, I've still finished grows and come out the other side with some pretty sweet bud. But I aspire to get familiar enough with the nutrients and growing to have a healthy plant all the way through.