It’s not spammy and a sketchbook topic is the place to put your images that are sketches and initial works.
You can only have five sketchbook topics on the forum so bear that in mind as you create them.
See this topic: Topic limit in Sketchbook Category now enforced
At this early stage, it might be a good idea to consider having five different ‘themes’ for your five different sketchbook topics. (One of them could be ‘Mei’s Random Stuff’ if you like.)
There is also a WIP (Work In Progress) category intended to show the development stages of a single image before you post the final developed image in a Finished Artwork category topic.