Don't forget about "unadvertised vacancies" awarded once the final bid is released.

For example, if enough 320 FOs in a base bid larger equipment (or a different base) and the staffing drops below the published minimum there will be 320 awards for that BES despite the fact that no vacancies were originally advertised.

Always bid what you want.

In theory, manpower planning could staff the entire airline by only advertising vacancies in the widebody CA seats as senior pilots retire and let all the remaining movement occur "naturally."