nice bud i liked that i have watched some videos with him as well thanks. the way i had it laid out to me years back, and you can see like he said only one back cross to each p1 parent is done.
p1{true breeding} X p1
this gives you a true f1 like a burpless cucumber it creates a phenomenon known as hybrid vigor where it takes the best traits from both parents combine them in the best way they could be, grow faster, more healthy, and yield more.
f1 X f1
this gives you an f2 they will so any combination of traits from the p1s
f2 X p1 mother
this is the f3 gen you will cross two f3s
f3 X f3
this is your f4
f4 X p1 father
now you are at f5
f5 X f5
now you are at a f6 and all should be stable by now you will cross this back to the p1 mother as a test of stability
and if not back as many gens as needed. this takes a lot of clones, time, effort, space, luck, and skill. no seed companies put these out you would only get the f1 from most. if they took the time the other companies would buy a pack grow them out, cross them and sell there own f1s.