I use one gallon jugs for my watering and do my nutrients per gallon. I mix up roughly what I think I'll be using (for example the recent run of autos I did had about 3.5g of soil each and 4 cloth bags so I did about 6g of feed or water at a feed. I prefer to feed slowly to help evenly soak so I use a 1L watering can with a small aperture spout and do 1L each pot until they're running off and then until the saucers are full (my plants are raised above the saucers.
If I were doing more plants or bigger, I'd just mix in larger containers (2gal, 5 gal, etc) and get that distributed. In the end, it's not about 'I gave this plant 1g. it's more about I watered/fed until the soil holds all it can and also the runoff has helped push out the old stuff.
What I did learn the hard way, is that if you're not watering to runoff, you'll most likely lock out later on if you're not in a living soil/hot soil and are feeding salts, etc. Then you have to flush in a more serious way to get back to where you need to be.