Here we go again.
If you wanna whine about water changes and I've seen folks talk lots of smack about EI, then you'll need to level the playing field and go after folks in the ADA contest, at least the top winning groups and Amano himself, not to do those same 50% weekly water changes.
Essentially, it's the same thing, adding ferts and then doing water changes to reset things. the only real difference is adding ferts to the sediment + water column vs Water column only. If you do not have ADA aqua soil etc, or a nutrient rich sediment(macros), then EI will work much better than the strict ADA liquid ferts.
If your goal is fewer water changes, then change your method
Do not expect an ADA tank, extremely high growth rates, extremely high light etc.
Try low light+ CO2, such tanks can go months without water changes.
If you want no water changes at all really, non CO2 will be years even.
It depends on your goal, what results you are hoping for and if you have the patience to do a non CO2 tank. We had no choice in the old days, most everyone did non CO2
Put another way, if you are too lazy to do water changes routinely, it's also very likely you will not prune often either, so you should reduce the rate of growth.
I guess all the breeders that do frequent water changes could likely get away with fewer water changes, but more certainly does not hurt and keep their routines and care very pro active and on top of things?
You cannot, near as I can tell with CO2 and Excel dosing methods, over do water changes. It's an extremely simple tool any fish keeper can easily use.
Hoses can transport water anywhere in a home without labor, lifting etc, semi automated or fully automated systems can be set up as well.
Reasonable fish loads, reasonable light levels, good basic care = fewer fish deaths, better plant health, less algae.
It's really a trade off how much and many to do, but more will never hurt and can only help. By the time someone gets around to doing a water change, does not take that much more time/energy to do 20% vs 50%.
99% of the Breeders, ADA, myself, commercial operations and dozens of other folks in the know suggest it. Perhaps we are all wrong?
Still, go non CO2 and/or reduce light if that(fewer/less water changes) is the goal.
Some tanks will be able to handle fewer water changes, others will respond better with more. Still, both will do great with larger rather than smaller changes in virtually all cases. I think the WC issue is more human psychology and getting the motivation to do them rather than anything else.
I freely admit I can be lazy about them, so knowing this, I try and account and plan for this by setting up easy to do water changes, semi automated methods, gives me a good excuse to clean and prune without my entire wet arm flalling about or submerging my head. That's a lot easier and cheaper to do than testing and micro management and rules out more unknowns.
You cannot automated testing. But you can reduce the amount of testing or water changes then your potential for errors goes way up, same trade off with reducing water changes.
So both result in partial estimations.
The questions becomes how far can you go without causing real harm to the system and how much error and safety do you want to build into your method?
Should we teeter on the edge or have a nice wide margin of safety?
I'll let you all answer that question.