Declutter a Room Without Turning It Into a Weekend Project

Decluttering approaches that start with everything out of the cupboard and work through the whole room in one go fail because they require the session to finish before the room is liveable again. The version that actually gets done works in bounded sessions where each one produces visible progress and the hardest category has a decision rule rather than a maybe pile that persists for months.

I want to declutter [specific room or area] but every time I start I end up with piles everywhere and lose momentum before finishing. Help me design a declutter approach that: can be done in sessions of [available time: 30 minutes, 1 hour, or a half day], produces a visible result at the end of each session rather than intermediate chaos, handles the items I am unsure about without creating a permanent holding pile, and gives me a decision rule for the specific category of things I find hardest to let go of: [describe what that is, such as gifts, things that might be useful one day, or things with sentimental value].