I also build doorway pages separately, and out of 5 million posts, I deleted 4 million—meaning 80% of the content was wiped out.
How did this affect traffic?
So far, I don’t see a clear upward trend for projects that were not penalized.
As for sites that recovered from penalties as a result of these actions: one site dropped from 250 unique visitors to zero, but now the filter was lifted, and daily visits broke a peak of 1,500 unique visitors yesterday—screenshot above.
Another example: a site was stagnating at 1,000 uniques and almost rolled down to zero—now it hit a record traffic peak of 2,100 unique visitors in 24 hours:
However, one problem occurred: a large site hit a filter, even though I deleted about 50% of its content. From 6k uniques down to 500 uniques per day:
So while some sites recover and show growth, one major site plummeted so hard that it offset the gains from the others.