can i just ask where that theory comes from Cheesejawa?
CT +CT = CT, CT+ VT= mixture of half this and thats. Most betta breeders want to keep strains pure by sticking to one fin type together like pairing crowntail m's and f's together so the offspring will mostly be crowntail, taking the best crowning and carrying on the strain forever trying to improve it rather than mix it all up.
Put it to you like this: (figures pulled out of my head)
Pure CT male show quality= $60 per fish
Pure CT female show quality= $30 per fish
Those two pair up and you raise 40 of the best fry resulting in pure CT's similar to the parents, worth the equal of the parents $30-$60 per fish depending on sex
Pure CT male show quality= $60 per fish
Pure Halfmoon female show quality = $30 per fish
These two pair up and will result in hm's with a comb edge, or "bitsa" bettas (bitta this, bitta that) raising 40 of these fry would result in fish with mixed strains, that will take a lot of selective breeding to breed pure strain from their offspring and resulting fish wouldn't be worth as much as pure strains.
Also the different fin varieties look a lot better when they are pure.