I hate to say it, but this is true.
Your site will remain in the guts of Google for quite some time until Google allows it to spring out.
Now, the issue is when and there is no one-size-fits-all answer.
I wish there is, but there isn't.
A factor to consider is the competitiveness of your niche.
Did you bother to target a less competitive sub-niche?
What kind of keywords are you going after?
There are many other questions that you need to ask so you can get an educated guess as to how long you're going to stay in the Sandbox.
One quick workaround
The good news is there is a quick way to get out of the Sandbox sooner rather than later.
This involves typing in your target keyword in Google and scraping the autocomplete results.
Once you have the list, feed them into an SEO tool like Ahrefs or Semrush.
The tool will tell you the keyword difficulty and the estimated monthly search volume for that keyword or question.
Toss out the results that have data in those tools.
You'd still be left with a long list of questions.
Now, filter those questions based on how relevant they are to your niche and cluster base them on how similar they are to each other.
Write content based on them.
You may be asking, "what about return on effort?" Good question.
Pack in as much of those related questions in a piece of content.
That way, your content will pull different streams of traffic with the same piece.
Even if it turns out that a long-tail question poses only ten searches a month and you get 40% ranking number one, that's still 40 visitors.
And if there are many questions on that page, it adds up.
The best part is you have a higher chance of ranking with those keywords that nobody else bothers with.
This is the beauty of this strategy because nobody bothers with those keywords because when you enter them in SEO tools, you get a big, fat goose egg.
Who on their right mind would target those?
But here's the secret: Google autocomplete doesn't show them for no good reason.
People are searching for them, but it's anybody's guess how much traffic you would get.
Specialize on those, and your domain authority will rise faster than you think.
And once you start dominating those longer search terms, start gunning after more competitive terms.
That's how you blast out of the Google Sandbox sooner than later, and that's how you build a firm foundation for your website.