How to have round robin effect for many coroutines execution sequence?

Support
1

Imagine you have Coroutine of type A. Coroutine of type B. Coroutine of type C.

You launch very quickly 1000 A, then 1000 B, then 1000 C coroutines == 3000 coroutines.

How to ensure that on each Thread coroutines will be executed in round robin order:
A, then B, then C
A, then B, then C
A, then B, then C
A, then B, then C
…

Currently it more looks like they will be executed like:
1000 A
1000 B
1000 C

Am I correct ??

2

Are the coroutines independent or linked? For example, does the tenth A coroutine have to complete before the tenth B coroutine starts?

Why do you want them to execute in round robin order?