I am auditing GA implementation for a startup and found they have a separate property for each of its subdomains. And yes, it is possible to navigate from subdomain to root domain and vice versa.

Each subdomain has a specific function as a blog or guide: (blog.example.com) and tools (tools.example.com) various tools user can use.

This is also true for Google Search Console as well.

Now the question is: is above setup correct? Since each property will have its own TrackingId how will this affect reporting?

Or should I just remove all subdomain property?

PS: I am using Google Universal Analytics and managing all of that with GTM.