Joanne brings up an excellent point in her question and response:
When a writer makes a reader “wander around” and “go deeper,” is there a risk of losing the reader’s interest?
I suspect many hours are spent discussing the layout of a Target store to maximize product visibility without confounding shoppers to the point they leave empty-handed and frustrated. A writer needs to keep the same concern in mind when creating a sense of mystery and suspense.
You, as a writer, should wander around during the first drafts to discover ideas you may not have discovered originally.
You may discover characters, symbols, deeper plot lines that you never would have found before. In your final draft, of course, you will make sure that every word counts. Every plot, symbol, and character relates to your main idea/theme. And as long as you create suspense/conflict on every page, your reader will stay right along with you.