in the 70s and 80s they made great strides with the carcass size of turkeys, then they hit a slower growth curve, but they still grow just a little bigger each year.
personally I am working towards a covey of young birds over 14 oz laying 16g eggs consistently. where the mean, median and mode show some uniformity of carcass size and growth rate.
Right now, I am actually very happy with our birds, I took some marinated to a BBQ today and they were the hit of the party.
I just may have the fewest birds of our more established coveys, I am just closing in on 36 hens that have all made weights and cuts.
but I'm about maxed out until fall and cooler weather. I hear Rhode Island and Colorado are about to have more and more Tatankas.
but anyone just starting, just keep the fastest growing, larger birds that lay the larger eggs, and repeat.