Google’s John Mueller: it takes time until Google sees your quality improvements

“These types of changes take time. It’s something where the algorithm has to reevaluate your whole website overall and a lot of low quality pages, they can play a role here. But sometimes there’s just so many other factors that come into play and that’s something that doesn’t just jump back up.

If you remove one part, you really have to think about: ‘What can I do across the whole website to make sure that it’s significantly better?’ […]

Even if you make big changes with the design and the functionality, and you add new features and things, I would definitely expect that to take multiple months, maybe half a year, maybe longer, for that to be reflected in search because it is something that really needs to be re-evaluated by the systems overall. […]

Low quality pages tend to be recrawled much less frequently by Googlebot – it is not unusual for six months to go by between Googlebot crawls on low quality pages or sections of a site. So it can take an incredibly long time for Google to recrawl and then reevaluate those pages for ranking purposes.”

“There is always the possibility that some of the removed content was actually adding value to the site, and with it suddenly removed, rankings can actually go down for a site.

This is one of the main reasons that Google always suggests improving content rather than removing it. Improving it means that the rankings can only go up, whereas by removing it, can cause loss of rankings instead of the gains that some people think content removals will do.”