Deployment Strategies

Let's talk about how to deploy sites?
When and when not to use features?
Writing hook_updates_N when and when not to.
Jenkins or other deployment tools?
Git and other version control tools and how they are being used.

As a team what does the workflow look like.

Quality assurance when and how?

Testing?

It would be nice to talk with other freelancers, smal lshops and big shops how they are doing with this and any gotchas they have avoided etc.