Again I'm unfamiliar with these
nutrients. But with any
nutrient calculator I have seen, when they refer to week 1, week 2, week 3 etc., they are referring to doing a nutrient change. Meaning that you would dump the previous weeks nutrients and make a fresh batch. That said, there is a whole lot of variables to consider. Any company's nutrient calculator should only be taken as a guideline to start with. From there, the grower makes their own adjustments (that's the fun part).
If you look at the first weeks numbers
Cocos A, 5.5 ml
Cocos B, 5.5 ml
Then look at the week two's numbers
Cocos A, 6 ml
Cocos B, 6 ml
You can see that the numbers are proportional, but slightly higher in week two. That's because the plants are older at that stage and a higher nutrient concentration is generally better at that stage. But if you were to add week twos nutrients to the same solution as you started with (week one), you would be just about doubling the strength of the solution. That would be a shock, not to mention too strong for the plants. Also there are usually different stages of growth, (vegetative/fruiting) that affect the nutrient concentration, and/or proportions.
It's also important to consider that plants don't take up nutrient proportionally. So just because the cocos A, and cocos B were proportional in the beginning of week one. Simply adding .5 more for week two wont make it proportional again (yet slightly stronger). Thus the reason for changing the nutrient solution altogether, that brings back the nutrient elements to a balanced proportions regardless of how strong they are mixed (5.5, 6.0, 6.5 etc.). However you may find for your plants you prefer different proportions. But that dosen't change the fact that the plants don't uptake the nutrients proportionally. So any company's nutrient calculator is just a guideline to start from, and changing it is the only sure way to bring it back in balance again. Though the larger the water volume the slower the nutrient will go out of balance (one of those variables I mentioned). As the grower gains experience they generally mix the nutrients as they see fit based on how their plants respond to their systems and any changes. At witch point week one, week two, etc. calculator measurements are fairly pointless (and again just a guideline). You'll probably just abandon the calculator, and just mix as you want within 2 months anyhow.
P.S.
Flushing the system is important, but often a source for manufactures to try and sell products. To be honest I haven't bothered to read the section on flushing in the calculator you posted. Simply because I have read a lot of things about reasons to flush before. As for the reason to flush before harvest I have seen no verifiable documentation (that's creditable) that subjecting the roots/plants to plain water or a flushing agent prior to harvest improves taste. That's just a company trying to sell you a product, or a employee that's just repeating what the company tells them to say to sell a product.
Flushing should be done regularly. The reason is to dissolve built up salts in the root zone (growing media). The built up salts can cause nutrient lockout. That can happen throughout the plants life, "NOT" just before harvest. It will affect flavor of the fruit the entire time the fruit is growing, and can't be fixed by a last minute flushing.