Advice about clearing out a house concentrates almost entirely on what to keep and what to let go. In practice the sessions that fail rarely fail on judgement. They fail at the two-hour mark, when the room is at its worst, the person is hungry, and stopping is far more attractive than continuing.
So the practical conditions deserve as much thought as the sorting rules, and they take ten minutes to set up.
Set out what you need before you touch anything
Bin bags, a box for donations, a marker pen, a damp cloth, and a bottle of water within reach. Every one of those, fetched mid-session, is an interruption that takes you out of the room, and leaving the room is how a session ends prematurely. Get them first and the next three hours have no reason to break.
Sound, and what it is actually for
Something playing helps most people, but the choice matters more than it seems. Anything with words you want to follow turns a decision about a shelf into a pause, and anything new competes for the same attention the sorting needs. Familiar albums, instrumental music or background radio work because they occupy the part of the mind that otherwise starts narrating.
A podcast or audiobook is the common trap: genuinely enjoyable, and it halves the rate at which the work gets done because interesting passages stop your hands. Save those for the mechanical end of the job, bagging up and carrying out.
Pick the hours you are actually any good
Sorting is decision-making, and decision-making degrades through the day for most people. A session starting at nine on a Saturday covers far more ground than the same session at four in the afternoon, when everything starts looking like a keep because keeping requires no thought.
Get light into the room
Poor light makes a job feel longer and hides the state of things, especially fabric and anything that has been in a loft. Open everything, put a lamp on even in daytime, and accept that the room is going to look considerably worse under proper light than it did under a single overhead bulb. That is informative rather than discouraging.
Work in stretches with proper breaks
Forty or fifty minutes, then stop properly: leave the room, drink something, do not start reading anything. The break that fails is the one taken in the middle of the mess with a found object in your hand, because that is how an hour goes on a box of photographs.
Have the exit sorted in advance
Know where the donations are going and when, before you begin. A bag with nowhere to go lingers by the front door for weeks, and items drift back out of it one at a time, which unpicks the session afterwards and is deeply demoralising to notice.
Finish on something visible
Spend the last ten minutes making one part of the room properly finished rather than spreading the effort evenly. Walking back in that evening to one clear surface is what makes the next session happen. A room that is uniformly half-done reads as no progress at all, even when a great deal has gone out of the door.