Either / both - depends. It’s a good practice to sketch because it’s easier to add crap on the screen. Sketching forces you to identify the easiest UX and to minimize distractions.
I sometimes skip though if I have a good idea of what I want to see
Discussion
That’s how I like to start. Whiteboard is my favorite. It allows you to work through the overall UX paths, not feeling like you’ve committed to anything so you are free to change as the ideas flow. Only after it’s mostly figured out to I head to high fidelity.
Yeah that’s the best! Being able to change things without feeling like you sank time into it already is ideal.