There is the saying "do as I say, not as I do." That is often the case in which Google prefers you to listen to their advice versus watch their actions. When Google AdWords redirected to Google Ads and used a 302 redirect, which is still the type of redirect in place, that would be one of those examples. AdWords has permanently changing to Google Ads, so why a temporary redirect?
Another example is when Google Maps moved from maps.google.com to google.com/maps, again a 302 redirect. Or when Google webmaster tools, well, it is still undergoing, moved from a google.com/webmasters and is moving to subdomain at https://search.google.com/search-console.
Again, do as we say, not as we do.
Why does this happen? Well, John Mueller of Google said on Twitter that often these decisions are not coming from the SEO team but rather the PMs (project managers) or other people in the company. This is a decision made by PMs, marketing, & security policies and not SEO and thus, we should not always just blindly follow what others are doing, even Google.
John said: "you'd be surprised (or maybe it's just like most other companies) how these decisions usually aren't driven by SEO."
Here is the tweet:
You'd be surprised (or maybe it's just like most other companies) how these decisions usually aren't driven by SEO, but rather PMs, marketing, & security policies. It makes it fun to see what external folks read into it though :-).
— John ☆.o(≧▽≦)o.☆ (@JohnMu) July 31, 2018
So if you think you should move from a subdomain to a subfolder or use a 302 over a 301 - it doesn't mean Google is doing this because it is their best SEO bet - it was just a decision made for one of many other reasons.
Forum discussion at Twitter.
