Having 1000 ppms in your medium doesn't make your plants take them up any faster. This is just my opinion, for whatever it is worth. But its working for me!
I've been running about 500 seedling, 800 early veg, 1140 full veg/bloom. That's worked very well for me.
I agree that it's tiring to mix various proportions. That was the original appeal of switching to Grow More Sea Grow. Just a tsp of dry nutes. It's all-purpose (16-16-16) through veg (similar simplicity in bloom).
Going to your point: feeding a static all-purpose like that demonstrates the fine-tuned weekly ratio (feeding schedules) are probably overkill. On the other hand, it also demonstrates that supplying additional nute strength (the higher N-P amount) isn't detrimental.
There's probably many variables involved. Buffering compounds, chelation, organic/synthetic, etc. I'm finding stronger (than your numbers) work well. But, I'm starting to agree that weekly fine-tuning of proportions is probably unnecessary.