If you've been following my coverage here on confirmed Google search algorithm updates over the years, you would see that the dates Google gives to the start of an update and, more often, the completion of an update are not always so exact.
Like with the December 2022 helpful content update, Google said it kind of started on December 5th but said they didn't post about it until the day after because it wasn't really noticeable until December 6th.
Also, when updates are completed, Google often says that some updates are mostly complete on a specific day but say some things can linger.
Just the other day, Google updated its Google updates page to add an end date to the March 2022 product reviews update. For some reason it was missing, I told Google about it (maybe others did too?) and Google updated the date to say it finished on April 6, 2022.
But I noticed that originally, Google told us that update was done a week later on April 11, 2022, not April 6, 2022.
April 6th does seem wrong? I mean @akent99 said it was done on April 11th https://t.co/oHE9D3xGjP
— Barry Schwartz (@rustybrick) January 3, 2023
So I asked Google what is up? Why give us a different date?
John Mueller of Google replied on Mastodon saying, "It's hard picking a date for some of these (especially afterwards). For many (not all) updates, the update rolls out, it takes a while to be visible (which is when we call it a start), and it takes a while to be in most queries / URLs / datacenters (which is when we call it done). There's no binary border for start / stop, it's more about "starts being visible" and "mostly settled down". It's a bit like timing when bread rises when you bake it."
Alan Kent from Google said something similar:
When I checked on April 11th it was "done". But it was actually "done" earlier.
— Alan Kent (@akent99) January 3, 2023
"Done" is a grey definition as systems roll out across multiple data centers and and process backlogs at different rates. So its really do we say done at 99.9% or 99.99% or ... (I'm done)
So while some Google updates have pretty solid dates, it seems others do not because they are more fluid in how they roll out.
Of course, this can cause a lot more confusion and possibly even distrust on these updates - but at least Google is trying to explain why the dates do not always fit into a specific calendar box.
Forum discussion at Mastodon.