Customer discovery and user interviews are essential to building a great product (in most cases, anyway). I will love to hear how you go about it. Let me kick-off the discussion.
I find it helpful is to think about user conversations in the form of sprints. In a 2-3 week time-boxed period, you have 3 stages:
For me personally 1-2 days of down time at the end of the sprint is also helpful to restore my energy.
This way you are speaking to users and continuously getting feedback every week, but you have 2 benefits:
you get a reasonable number of conversations in before you make drastic changes (opportunity for real validation)
you get time to really absorb the learning and recover your energy (this is the most important part in my opinion! It's too easy to forget / blur conversations after a point)
At Loop, we are using this approach and are enjoying the process (in addition to being more productive!) It sounds simple but I had messed this up when working on my first from-scratch product.
The time-boxing and downtime is important!