Google Treats Some Subdomains as a Single Site, Not Multiple Sites
"During Mueller’s answer, he commented that Google is really good at being able to recognize a single website across multiple subdomains versus when it is multiple different (and often unrelated) sites across those multiple subdomains:
"From my point of view, you can definitely use subdomains if that works better for you, go for it. That’s not something where I’d say you’d be worse off on subdomains.
"We do try and understand the structure of the sites so if you have one normal website spread out across a lot of subdomains, which we sometimes see people have wildcard subdomains set up, then we’ll probably recognize it as one site, where as if we recognize that there are multiple sites running subdomains, we will recognize them as multiple sites.
"So it’s not necessarily something where it always goes one or the other."
Google Treats Some Subdomains as Single Site, Not Multiple Sites
