Depends on the changes I’d say. If it’s a change marked as [BREAKING] then definitely it’s safest to provision a new server. If for example we changed the template of an Nginx config file, it’s likely fine to re-provision an existing server.
We don’t really provide that information beyond [BREAKING] so it’s a bit of a judgement call. All that being said, provisioning a new server is a great habit anyway in my opinion. It’s what we do for the roots.io site. It can be heavy-handed and take more time, but it’s safest in the long run.