The reality in 2020 is that if Google classifies your duplicate content as THIN content, or MANIPULATIVE BOILER-PLATE or NEAR DUPLICATE ‘SPUN’ content, then you probably DO have a severe problem that violates Google’s website performance recommendations and this ‘violation’ will need ‘cleaned’ up – if – of course – you intend to rank high in Google.
In Yoast SEO you can enter the keyword or keyphrase you’d like your post or page to rank for in the search results. We then run a check on your content to check whether you’re using the keywords often enough – but not too often – and in the right spots. In Yoast SEO Premium, we take this one major step further. We will not only check for the keyword or keyphrase you enter, but we will analyze your text on all variations of that word or phrase. If the keyphrase is “room decorating ideas” and the synonym is “apartment decorating ideas” all the possible word forms of each word are taken into account: ‘apartments’, ‘rooms’, ‘room’s’, ‘decorate’, ‘decorates’, ‘decorated’, ‘idea’, etc. This way, you are truly optimizing your text. With this addition in Yoast SEO Premium, we can guarantee that no other WordPress plugin comes closer to how Google will see your text*! * We are constantly working on perfecting this for all available languages
The actual content of your page itself is, of course, very important. Different types of pages will have different “jobs” – your cornerstone content asset that you want lots of folks to link to needs to be very different than your support content that you want to make sure your users find and get an answer from quickly. That said, Google has been increasingly favoring certain types of content, and as you build out any of the pages on your site, there are a few things to keep in mind:
QUOTE: “What makes a page spammy?: “Hidden text or links – may be exposed by selecting all page text and scrolling to the bottom (all text is highlighted), disabling CSS/Javascript, or viewing source code. Sneaky redirects – redirecting through several URLs, rotating destination domains cloaking with JavaScript redirects and 100% frame. Keyword stuffing – no percentage or keyword density given; this is up to the rater. PPC ads that only serve to make money, not help users. Copied/scraped content and PPC ads. Feeds with PPC ads. Doorway pages – multiple landing pages that all direct user to the same destination. Templates and other computer-generated pages mass-produced, marked by copied content and/or slight keyword variations. Copied message boards with no other page content. Fake search pages with PPC ads. Fake blogs with PPC ads, identified by copied/scraped or nonsensical spun content. Thin affiliate sites that only exist to make money, identified by checkout on a different domain, image properties showing origination at another URL, lack of original content, different WhoIs registrants of the two domains in question. Pure PPC pages with little to no content. Parked domains” Miranda Miller, SEW, 2011
Ask for a technical and search audit for your site to learn what they think needs to be done, why, and what the expected outcome should be. You'll probably have to pay for this. You will probably have to give them read-only access to your site on Search Console. (At this stage, don't grant them write access.) Your prospective SEO should be able to give you realistic estimates of improvement, and an estimate of the work involved. If they guarantee you that their changes will give you first place in search results, find someone else.
QUOTE: “I think there is probably a misunderstanding that there’s this one site-wide number that Google keeps for all websites and that’s not the case.  We look at lots of different factors and there’s not just this one site-wide quality score that we look at. So we try to look at a variety of different signals that come together, some of them are per page, some of them are more per site, but it’s not the case where there’s one number and it comes from these five pages on your website.” John Mueller, Google 2016
QUOTE: “(Google Panda) measures the quality of a site pretty much by looking at the vast majority of the pages at least. But essentially allows us to take quality of the whole site into account when ranking pages from that particular site and adjust the ranking accordingly for the pages. So essentially, if you want a blunt answer, it will not devalue, it will actually demote. Basically, we figured that site is trying to game our systems, and unfortunately, successfully. So we will adjust the rank. We will push the site back just to make sure that it’s not working anymore.”  Gary Illyes, Google 2016

Your website is the “hub” of your online brand – so, it’s important to have regular checkups to ensure everything is in order. It’s also important to note that your website is a living digital property, it’s typically not stagnant for long periods of time. In any given year, content is added and/or removed from your site. It is for this reason that audits should occur on a regular basis. We recommend that websites be audited at a minimum of once per year. That allows your teams to fix critical issues as they arise.