Aloha,
If you breed tufted to tufted, and put 8 eggs in the incubator, 1/4 or 2 will be homozygous for tufted(TT) and die before hatching. 1/2 or 4 will be heterozygous(Tt) and therefore have tufts. 1/4 or the remaining 2 will not have the tuft gene(tt). So you will have 6 chicks, 4 tufted.
If you breed tufted to clean face and put 8 eggs in the incubator, 1/2 or 4 will be heterozygous(Tt) and have tufts. the other half or 4 will not have the tufted gene. So you could have 8 chicks but still, only 4 will be tufted. Either way, you get 4 tufted chicks.
Of course, these numbers represent the perfect world and not the real world, as the real world does not always get you heads 50% of the time when you flip the coin.
At this point, Iʻd rather have a higher ratio of tufted and would be willing to have a lower percentage hatch to get a higher percentage of tufted chicks.
Of course, itʻs moot for me as none of my hens have tufts, but luckily, both of my roosters have tufts.
Aloha, Puhi