We use hundreds of non mut females and then breed them with the male of our choice (for whatever stat we want to improve) with the goal of hitting a male with the mutated stat.
We breed every two days currently for HP and then melee on rexes. So every four days we increase the stat for melee and Hp. Then at some point you mix them together. Many times we hit females as well which is good to mix back with the other stats.
If possible, I recommend mixing the other stats into the non mut line so that they’re guaranteed to hit (oxygen/food/weight/stamina). That way you have a full line of female non mut breeders with identical stats. Event colors are a good addition as well since they don’t take mutations to hit. We have different Easter tamed males that we’ve used to create non mut females that are 2, 3 or even 4 color. When we get the color and stats right on a non mut female, we clone it as much as we want and then add it to the breeding pile.
With extinction, you can feasibly start up a breeding program in a week if you have 15-20 cloners and a good base female to use, assuming the dino is cheap enough to clone and you have enough element. Our rex breeders despawned after extinction came out so we had to start over and it only took us 10 days to do so.