It’s both easier for the creator and, typically, better for the final product if one moves from low fidelity to high fidelity during a design process.
I was working on a Power Point presentation recently and I kept putting it off and worrying about it until finally I just sat down and said I wouldn’t even open up Power Point, I’d just open up my very simple text editor and write out my ideas for the content of each slide. In this very low fidelity, rough environment I found I had the basic presentation outlined in only 15 minutes and was now far more excited to move up the chain into Power Point.
Intermediary levels of fidelity are also often helpful. With software design, after sketching something on a napkin, outlining something in grayscale in a wireframing tool like Balsamiq can be useful to help you really think harder solely about layout without cluttering your mind additional choices around color and texture. This wire-framing is like the clay model phase in the fidelity ladder used during car design — designers solely look at the shape and contours without the other concerns that start to creep in at the next levels of fidelity.
I’ve had so many productive sessions when I shut off my computer completely and just sketch or bullet point my ideas on a piece of paper.