As ever in MLO, there are more than one ways of doing things(!)
A) Folders
The slight problem with using MLO Folders to define Area of Life (Work, Recreation, Family etc) is that you need to move every single item you add into the correct Folder. If like me you have several hundred tasks that can be a lot of tasks scroll & click past.
B) Flags
Another way you could think of doing this would be with Flags. When you create sub-tasks, the 'child' tasks Flags do not automatically inherit from their Flag setting from their 'parent' task.
C) Context/Tags
Another thing you could try would be using tags (AKA contexts), which do inherit from parents. It gets slightly messy if you are using tags for actual Context but it works.
Fwiw, if you want something more advanced, at present I am experimenting with using a combination of A) and C) whereby each of my Folders has the relevant context-tags I want already set up.
Then when I insert a task into a folder, it will automatically default to having the same context-tags.
And if I add tasks via the Inbox, I can then there is a useful command in MLO to make sure that all subtasks contain at least those of the parent in question. What is clever is that it does not over-write the context-tags (that may be genuine real-world contexts) that each child task may have . If you are interested, the command is found here:
View > Advanced > "Add context to all subtasks". For convenience I have set it up on a hotkey.
I still find moving stuff around to be pain, and where possible I just insert new tasks where I want them.
Another thing that I am experimenting with and so far am finding to be extremely it to mark tasks up with colour depending on:
a) their context-tags
b) whether or not they are a task with no children (i.e. this means that each item is an 'Action' or is an MLO Project that has no Actions [in which case the implied action is decide what new action is required or else mark the project as complete!] )
e.g. I am finding it really nice for my items that are both Active (i.e. of status "do ASAP") and are actionable Actions (rather than Project Outcomes) to leap out at me in a specific colour.
J