I've been through several RTM schemes - they work for a while, and then either I get bored or the weaknesses of the system drive me to rewire everything. Here's my latest rewire:

Only 5 Lists (including Inbox):
- Inbox: Tasks that need to be dispositioned into another list, reviewed daily (see "Open" smartlist below).
- Active: Tasks that I'm working on (or are scheduled)
- Queue: Tasks I want to get to, reviewed weekly.
- Someday: Tasks I might consider, reviewed monthly.
- Delegated: Tasks I'm tracking with others, but not responsible for (using tags so that I can see all tasks that are delegated to Bob the Monkey, for example).

Locations for context:
- Work
- Home
- etc., as needed

But many Smartlists:
- Open: Tasks in the Inbox OR have no location set (i.e., need to be dispositioned, reviewed daily)
- Tasks: Tasks that take less than 15 min (or have no estimate)
- Jobs: Tasks that take 15 - 30 min
- Projects: Tasks that take more than 30 min

Then location-specific smartlists, as needed:
- WkActive: Location = work, list = Active
- WkTasks: Location = work, smartlist = Tasks
- And so on, but only as needed for what follows:

Then my working smartlists, tagged as "favorites" - these are the only lists I work from:
- 1WkActiveTasks: All my work tasks that are active and take less than 15 minutes, sorted by Priority and Due Date, grouped by Due Date.
- 2WkActiveJobs: Like previous, but 15-30 min.
- 3WkActiveProjects: Like previous, but > 30 min.
- 4HmActive: No need to break this out for home stuff into tasks, jobs, and projects.
- Whatever else I need like this. The number prefix keeps them sorted in the favorites list.

The sorting and grouping put the No Due Date items first, then dated items grouped by day in order below. Each group is sorted by priority. I can quickly see what needs attention first.

I use BLOCKS of time at work - some for tasks, some for jobs, and some for projects. So, I use the Favorite Smartlists to keep visible only what my current block of time is for, so that I can focus. I'm not starting at long projects in a list of other things that I can knock out in minutes. My smartlist shows only what applies to my time block.

If there are too many Jobs or Projects in view, then I need to change something in the task to get it out of view - I don't need to look at it.

I don't care that my 1WkActiveTasks smartlist shows a hundred tasks, because of the sorting - the no-date, priority, due-now tasks are what I see, no matter how long the list actually goes down the scroll. If too many are due today, then I change the date to be realistic with myself.

I use tags to collect like tasks, either by to whom I've delegated, a given project, a department at work, etc.

Details of smartlists:
Open: isLocated:false OR list:Inbox
Tasks: timeEstimate:"<6 minutes" OR hasTimeEstimate:false
Projects: timeEstimate:">29 minutes"
Jobs: NOT list:Tasks AND NOT list:Projects
WkActive: location:Work AND list:Active
WkTasks: location:Work AND list:Tasks
WkJobs: location:Work AND list:Jobs
WkProjects: location:Work AND list:Projects
(etc., as needed for each location)
1WkActiveTasks: list:WkTasks AND list:Active
2WkActiveJobs: list:WkJobs AND list:Active
3WkActiveProjects: list:WkProjects AND list:Active
4HmActive: location:Home AND list:Active

Daily: review Open
Weekly: review Queue (true list)
Monthly: review Someday (true list)

The key is to view only the list that corresponds to the block of time you're working.

Delegated items are reviewed by tag at whatever interval makes sense. Just create a task to remind you when for each one, with the same tag.