Sometimes, yes. But the bug might not immediately be obvious (for example a memory leak) or cause data corruption, in which case you need to get a backup - and

Sometimes, yes. But the bug might not immediately be obvious (for example a memory leak) or cause data corruption, in which case you need to get a backup - and you probably don't use a backup without manual approval. A good infrastructure will help you at every point, but it will still take time.