How to stop processing queue after processing x items successfully?

I want to send emails with an advanced queue queue (personalised weekly reports, no spam). My mass mailing provider allows me max. 100 emails per hour and max. 300 emails pro hours.

How can I stop processing queue after processing x items successfully?

And how can I avoid an advanced queue queue during cron, if several requirements are met?

Thanks in advance for your hints 🙂