Am I missing something here Buddy? You mix your Nutrients by the volume of water correct? No matter if you hand water or if you have a watering system, if they both have the same volume of water you would still need the same amount of Nutrients.
The biggest thing it would save you would be time, but isn't it best to spend time with your plants to get to know them, understand whats going on with them, see what they need, constantly be involved in their medium?
I have 3 Rooms each with 10 1,000 Watters (2 used to have 8 1,000 Watters), and I watered for years by "myself" with filling up a Huge Plastic Pickle Barrel in each room, measuring the Nutrients, PHing the water and using a pump and water wand to hand water each room. Takes hours. Now thankfully I have someone to do that for me as I take care of the Breeding aspect. But it is still done the same way (just not by me).
That's quite a bit my friend like fuck me haha .. I think I have better way of explaining why it bugs me so much about this nutrient thing. What I do to water is take out 3 plants at a time and put them in a 10x20 clone tray fill up a 32oz gatorade bottle with my nutrient solution. Then I water each plant counting to 7 on each one which gives them a equal amount with 10% run off (took some time to figure haha) and then dump my runoff into a empty gal milk jug. Well it don't take long till fill up I mean shit by the end of my 2nd watering I have around over half a gal almost 3/4 which I started thinking about cuz all I do is dump it down the toilet. I'm like shit man I'm wasting so much!!! Especially being a recycling keep it green kinda guy that I am so I started thinking about recirculating systems and was like all that shit I'm tossing would be used so I'm wasting money here even though I didn't pay for these nutes. However I did pay for the Pure Blend Pro Grow and Bloom I used my first run so yea it's a waste IMO to hand water so many times a day. Don't get me wrong I'm loving my results but I get a extra week out of the same amount of nutrients with a recirculating system or ebb & flow so that's what I gotta get next. But believe me if I don't have enough to spend I'll just be getting the table and stick it on top my 18gal Roughneck Rubbermaid tote and hand water hahaha