I did some grows in DWC and soilless using Sensi Grow for veg and Connoisseur for flower both being two part nutes and found there to be too much N in flower, specifically late flower. I got the 3-part nutes almost three years ago, (used the 3-part for a decade before the 2-part), and after the stretch feed Lucas Formula style to reduce the N. It still gives them enough N for their needs but not so much it inhibits bud production. They still need lots of N during the stretch as they are building lots of new growth and it's essential for that.
More flexibility with the 3-part I find and I do add a bit of Epsom Salts to make sure they get enough Mg and some extra sulfur for the resin.
For those not familiar with the Lucas Formula method it basically drop the Grow and use half as much Micro as Bloom. If you look it up it will say X# of mls/L of each but I go by how much I want to raise my ppm without changing nutes. If they're lucky they get one change after the stretch for the whole grow.
With AN 3-part and likely GH too: I checked as I added 1ml/L of each to 2 different DWC tubs holding 50L each.
1ml/L Grow = 90ppm
" Micro = 140ppm
" Bloom = 110ppm
So by starting a new tub with clones and after adding the appropriate amount of CalMag I end up with just a bit over 300ppm which is just right for starting rooted clones in DWC. Then I just add more nutes to raise the ppm as the plants get bigger and can handle more.