Here is an opinion using my short experience and my experienced analytical skills:
- EI is about dosing with excess, this is fact,
- Having a stable ecosystem means persistence and no stress,
bare with me,
- Most of the time the rest day is just before the water change but at the fertilization peak. In most cases its Saturday after dosing 3 times micro and macro so there should be plenty of excess.
If you miss a day, you have two possibilities for which I still don't have a correct answer:
- Or plants would suffer, if your EI dosing cant cover that day (you haven't built up a good nutrients buffer in the water). But here you would see it observing your plants.
- Or plants usually buffer them selves, they are healthy, have no deficiencies, so in the end they are fine to have a wave in the river which lacks nutrients they are used to consume.
If you miss more days in a row - may be someone could share how long plants could live trough as I strongly believe (still I have no idea if 1 or 2 is "correct") that option 2 seems logical - if you exclude from the equation the permanent resources in the nature as light and may be CO2. May be also drastic water parameters changes are harmful ( and yes they are), but a day without a byte when you have been fed up for days could not be a problem.