Better post meta efficiency?

I work with websites which require using Post Meta for Post Objects within a particular Post Type.

I often add a Meta Box to a particular Post Type, to provide additional settings for the new Post Object being created.

You can imagine by now, I have created a few classes which make Post Meta management easier for my every day needs.

I have come to common practice of always prefixing all of my Custom Field keys. I have decided to always use my initials, and then a quick reference for what the fields are about.

So for example, if I were to add Visibility Settings to all Post Objects in a particular Post Type. A Custom Field key prefix might look like: mbe_visibility_.

So If I had a ‘Global’ Custom Field for the Post Object. It might look like: mbe_visibility_global.

I currently have a function that grabs all Custom Fields for the Post Object, then iterates through the fields returned, filtering out only the fields which have my field key prefix (mbe_visibility_).

So if I had three Custom Fields: Global, Post Types, and Posts, I would have three keys (each containing a value, specified when saving the Post Object): mbe_visibility_global, mbe_visibility_post_types, and mbe_visibility_posts.

Now here is where my questions begin to formulate.

I feel like it’s a little over-kill, fetching/filtering ALL Custom Fields assigned by WordPress core and other miscellaneous plugins on the website.

I was thinking about just changing the way Post Meta is stored/referenced for my Custom Fields.

Instead of saving a new Post Meta key for each of the Custom Fields, save all of the Custom Fields in ONE Post Meta key for that Post Object.

My approach was to just stick all of your $_POST data into one array. So an input field in a Meta Box might look like: <input type="checkbox" name="mbe_visibility[general][global_visibility]" value="'.$value.'" />

So now when you hook into save_post you only need to check if ONE key is available.

if(isset($_POST['mbe_visibility'])) and just save that entire array into one Post Meta key.

update_post_meta($post_id, 'mbe_visibility', $_POST['mbe_visibility']) should probably sanitize / validate the data before save, but this is just for example.

Now all I have to do, to reference ANY of my Custom Fields from the Post Object’s Post Meta, all I have to do is: get_post_meta($post_id, 'mbe_visibility', true) and I will have specifically what I want for this Post Object, and not have to fetch and filter through all sorts of other unneeded Post Meta from WordPress core or other miscellaneous plugins.

If you made it through my long-winded explanation, the question is: Is it a bad idea to store all of your custom fields into one post meta key, for easier data management? VS. Storing each of your custom fields in individual post meta keys for each custom field.

Of course I would like to see a valid explanation with reasoning supporting your answer.