Using cache-control: public, max-age=3600 with vary: Cookie can be valid, but there are important considerations:

1. Potential Issues:

- When you include `vary: Cookie`, each unique Cookie combination will create a different cache entry
- This can lead to cache fragmentation and reduced cache effectiveness
- If your site uses many different cookies, you might end up with many cached versions of the same page

1. When it's appropriate:

- If the page content actually varies based on cookies (e.g., user preferences)
- If you have a limited set of possible cookie combinations
- If you're using a caching system that can handle multiple variants efficiently

1. Better alternatives might be:

```http
# If the page doesn't depend on cookies:
cache-control: public, max-age=3600
# (remove the vary: Cookie header)

# If the page is user-specific:
cache-control: private, max-age=3600

# If only specific cookies matter:
vary: Cookie-Name
# (specify only the relevant cookie)
```

1. Best practices:

- Only use `vary: Cookie` if the content actually depends on cookies
- Consider splitting your content into:
  - Public cached content (no cookie dependency)
  - User-specific content (loaded dynamically)
- Use more specific cache-control directives if needed:
  ```http
  cache-control: public, max-age=3600, must-revalidate
  ```

The validity depends on your specific use case, but be aware of the caching implications.

To vary by specific cookie names, you can list them in the Vary header separated by commas. For example:

Vary: User-Prefs, Theme

However, I need to correct my previous response: You can't actually specify individual cookie names in the Vary header directly. The Vary header can only work with entire HTTP headers, not individual cookies.
If you want to cache based on specific cookies, you'll need to:

1. Extract those specific cookies into separate headers
2. Vary on those custom headers

Example approach:

# In your middleware or response handling:
def process_response(response):
    if 'user_prefs' in request.cookies:
        response.headers['X-User-Prefs'] = request.cookies['user_prefs']
    
    response.headers['Vary'] = 'X-User-Prefs'
    return response

Alternative approaches:

1. Use different URLs for different variations
2. Use client-side caching strategies
3. Implement custom caching logic in your application
4. Use a CDN that supports varying by specific cookies (some do)

The most common approach is to either cache everything (Vary: Cookie) or nothing cookie-related, rather than trying to cache based on specific cookies.

Let's break down cache-control: public, max-age=3600, must-revalidate:

1. public:

- Response can be cached by any cache (browsers, CDNs, proxies)
- Even if it's associated with HTTP authentication or HTTPS
- Opposite of `private` which would only allow browser caching

1. max-age=3600:

- Cache is considered fresh for 3600 seconds (1 hour)
- During this time, caches can serve the content without checking with the origin server
- After this time, the cache is "stale"

1. must-revalidate:

- Once the cache becomes stale (after max-age), the cache MUST revalidate with the origin server
- Cannot serve stale content even if the origin server is down
- Without this, some caches might serve stale content if the origin is unreachable

Example timeline:

t=0:          Client requests resource
              Server responds with fresh content + cache headers
t=1hour:      Cache becomes stale
t=1hour+1sec: New request comes in
              Cache MUST check with server before serving
              (If server unreachable, returns 504 error)

Common variations:

# Allow serving stale content if server is down:
Cache-Control: public, max-age=3600

# Never cache:
Cache-Control: no-store

# Validate every time:
Cache-Control: no-cache

# Private browser cache only:
Cache-Control: private, max-age=3600