so if they start new geenrations from seed, if i breeded jack herer with jack herer to get more jack seeds, then breeded plants from those seeds with sour diesel plants, would that be a f2 or f1?
jhxjh = jh f2 gen.
jh f2 gen x diesel results in jh2.1xdiesel, a new f1 cross.
you'll only get f2's and 3's and 4's etc through inbreeding. to do this, you must select a male and female from each generation to carry it to the next. there are no mother plants in ibl's.
on the other hand, some strains are f1 hybrids, and can only be made by crossing a certain female with a certain male. phenotypes play into f1's big time, as you can cross ak and romulan, and it will be different from my akxromulan, because the parents are different. offspring will not be the same.
to answer your q, if you want a stable batch that is uniform, you want a stable ibl (ie, skunk #1) (ibl = inbred line), or a f1 cross. f2's will give you variation, as only half of them will be the cross you seek, and 25% will be mom, and 25% will be dad.
ie
haze x dreamgoddess = purple haze
purple haze x purple haze = ph f2
ph f2 will consist of 25% haze phenos, 50% purple haze phenos, and 25% dreamgoddess phenos.