So, there's a concept associated with housekeeping and possessions, introduced by Dana K. White of A Slob Comes Clean: "Clutter Threshold". It's defined as the amount of stuff that you can keep under control.

Clutter Threshold doesn't care how much stuff you LIKE, or wish you could control. You may adore someone else's Victorian-eclectic living room with sixty knickknacks per square foot, but if you can only manage an ultra-minimalist number of possessions, your house will be out of control until you pare down to an ultra-minimalist number of possessions. If your possessions exceed your clutter threshold, you may be able to get it all nice and clean for a party or visitor, but it will rapidly revert to chaos.

Are you seeing where I'm going here?

We often hear of people starting GTD, getting their system perfect, and then sliding into chaos. I suddenly think that they are designing a GTD implementation that exceeds their clutter threshold.

They may WANT to manage a hundred project and a thousand actions, but if that exeeds their cutter threshold, it...exceeds their clutter threshold. It will not work. Even if those thousand actions all theoretically COULD be worked right now, and it feels like a lost opportunity not to have them all available, if they exceed your clutter threshold, the whole system will collapse.

So my recommendation is: If you can't keep your system under control, consider whether you need to declutter it. Multiple Someday/Maybe lists, many of them with review cycles much less frequent than a week, may be your friend.