I like @Lee-White 's advice on calling the preliminary concept sketches "thinkings" instead of drawings. To add to that, I always disliked putting "thinkings" into a sketchbook because I can have up to 5 (sometimes more) pages worth of thumbnails and sketches for one concept. Often the sketches are ugly because I'm just focused on throwing the ideas onto paper. I ended up doing less sketchbook work in general because of this.
Now I use a folder-style clipboard stocked with copy paper for my "thinkings" and it works great for me. It's inexpensive, reloadable, portable and I don't have to worry about having a nice drawing. Plus, I like that the pages are super easy to scan (no binding to interfere) and that I don't have to store loads of sketchbooks with work that I mostly dislike.
If there are sketches that I do like, I cut and glue (or tape) them into my journal and call it a day.
All in all, a great episode. I tend to have a million and one ideas for an illustration and then at the end of the day, play it safe (probably too safe) because I doubt my ability to get my far-out-there ideas out onto the page. It's good to know that it's better to go more wild to begin with and be wrangled back in than to play it safe and end up with a boring illustration.