I've run into this issue in many fields in which I'm interested in learning about. For the purposes of this question let's assume electricity/circuits/power systems. I find myself starting at the basics and as I try to understand each concept, I start thinking of more of how this concept really works instead of accepting it at face value. In addition to this I also start to ask more complicated questions which I'm assuming I could answer if I would read on. The problem I end up running into is I won't let myself continue until I understand the concept completely. For example: I start learning about how current is always consistent in a single circuit which makes me start thinking about how total current/draw is measured in a household. Then this leads me to think that if everything is connected by wires, then shouldn't this be one large circuit with the same current.
As you see I start diving too deep. This seems like an inefficient way of learning and it usually causes me more stress than understanding.