You can skip the sandbox if you hit a 0 comp keyword with high enough volume. Instant ranking.
But if it's just one keyword, most of your website will remain in the sandbox, so even better is to find a subniche that's underserved and has a lot of searches.
You need a little luck for this, so better research many options.
But in the grand scheme of things it doesn't matter if you skip the sandbox or not as long as you keep putting in the work.