There ais no clear answer to your question. When you use the term best practices, it can be misleading. Remember this one statement, what is good for me can poison you.
So with that said, a lot of it depends on your environment, your testing abilities and what you are developing. There is no magic answer and it all deoends on a lot of variables. Are these products inward or outward facing? Are they going to be SaaS applications, in the cloud, fat clients, etc. Are you using Agile Development methodlogies or waterfall? Are you a regulated industry or not, how big is your team, a small IT shop to you may be a big IT shop to me.
So to sum it up, there are many factors that your release schedule depends on, finding the right mix and the right way will take time.