So i haven’t used Bergman nutrients but I can tell you that all the “needs this and not that in this stage and not that stage” is WAY over rated 
Nutrients can be so easy and it dosen’t have to be different for each stage at all to have amazing results 
If you want the easiest nutrients then this is what you want.
One for veg and one for flower, no mixing any thing together as this series is a 1 part nutrients and contains npk and micronutrients and its not expensive
Absolutely nothing wrong with Jacks either, lots of people use it, but it is a 3part nutrient line so slightly little more to it then GH maxi series…
Check out my current grow to see what it can grow.