Question of forwarders vs. caching-only

[Don Awalt]

I have a question, I can set up a DNS for my own (non-authoritative) subnet
via a caching-only server. This appears to go to root DNS servers to resolve
names not in its own cache.  Or, I can additionally add the names of
"forwarder" DNS servers to forward the queries that cannot be resolved
locally.

When would I just let the DNS server cache via the DNS root servers, vs.
specifically forwarding? I am thinking forwarding makes sense when you can
point to another DNS on your own subnet vs. going to a root server
somewhere, but does it always make sense to forward to an authoritative DNS
server for your subnet (even if it's across a WAN, as are the root servers)?
When not to forward?

Thanks for the tips on this, I don't really see the distinction between
forwarding and caching only that seems to forward to root servers.