Small company here < 15 employees. No formal process at all. Change is managed (minimally) though and would take one of two forms depending on the project:

- Incrementing versions married to a document listing the main points about that version (that's the heavy version!)

- Release ad hoc based on change and issue tracking

With the size of the company we are lucky to get anyone beyond the developer to even look at test deployments before they go live. That's how you know it's a big and important change. Fortunately we mostly get it right - I would sometimes like a bit of help with that but what can you do? To be fair I like being fast acting and responsive - I've got used to it now.