8: Communicate with Customers/Users

Yes. Do that.

Not only should we follow Principle 7 of giving products to customers early, but we need to communicate with them. Not just feedback on the product itself; but stay in touch.
We need to have raport and a working relationship with our customer. As a product team, we need them to trust that they can tell us anything about their experience with, and suggestions for, the product we're having them use. This can't happen if we just have them use the product in a predefined way, or just send an email of "Latest pushed to test environment".
That won't do at all(.

Who is the user? Who is the customer? The users aren't always the customer. Though users are who we're building for. The leadership of the end user is important. They may never use the software, but they're another great source of information.

One thing I do with teams I work with as a technical coach is telling them that I want any and all feedback, and if they'd rather be anonymous, pass it through their manager. A lot of employees will feel more comfortable passing along information/feedback/ideas w/o their name attached. Make sure that's doable.
If we don't stay in touch with multiple levels of customers/users, we may miss out on important information. Changes in their organization may have significant impact to what we can deliver. New budgets, staffing changes, re-orgs... all things that can impact what we're delivering and when.

If our tool has parts, we need to be sure we're engaging a customer for each part. If there's different functionality for different access; user vs admin - It's important to ensure there's a user (ideally multiple users) for each level of access.

We can't ignore our customers; if we do - They won't find the value they could have in the software we deliver. And that's a failure on us, the development team.