We rotate the layer flock, never. The rooster has changed twice in 3yrs. The current model is starting to show some not-so-fine qualities, so he may end up in the pot sooner rather than later. We incubate the layers 3x/yr - we've lost a few to a fox, a few to a coyote, etc. So in order to keep the number of hens up, we incubate. We "Camp Frigidaire" the cockerals at about 16-20wks. Tasty, but lean on white meat, as they're heritage birds (Black Java's). Hens are now 3yrs old and still laying like champs...so only the wildlife gets to eat the girls (grumble, grumble, grumble - over MY dead body!). Not sure what'll happen to the hens when/if their laying days are done....haven't had to deal with that yet.
The meat flock, we grow to 10-12wks and they go to Camp. We've not tried to mingle the flocks or inter-breed, as I'm interested in the Java's as a closed heritage layer flock.