F1s have less variation than f2s. In the f2 generation you can make selections towards a trait but you won't know until you grow out the f3s if your picks worked in your favor.
Mendelian breeding theory is a bit dated and not totally applicable to pot because of so many traits and recessive genes being selected for, but should give you a better understanding of things. https://www.icmag.com/ic/showthread.php?t=26677
S1s are self pollinated plants using the reversed female you were talking about.
For the most part any question you can ask yourself is a Google search away from being answered.
yea this is where im mixed up...I thought F1's had more variation as you could get more of Say Strain A than Strain B in one...whereas the next seed could be side B dominant....whereas the F2's are the picked phenos back crossed to try and make it more 'stable'...thanks for the replies though gives me something to think about! ah well shame about the S1's unless the F2's I got which were the SD x SD by phinest cannabis!