You do not really see the holes until the room is empty. A year of picture hooks, one curtain rod, the shelf that went up fast and came down faster. None of it registered with furniture in front of it. Then the walls are bare, the light comes across them sideways, and somebody with a clipboard puts a number on every one.

The holes are not what costs you. The repair is. The usual route is a tub of filler, a wait, a sanding pass, and a dull ring around each spot that catches the light differently from the paint beside it. You fixed the hole and left a mark easier to see than the hole was.

The blade is the whole idea. You load the hole and pull the blade across it in one pass, the blade riding on the wall on both sides of it. The fill stops exactly where the wall surface already is. Flat is not something you sand your way back to. It is set by the pass.

Most of your holes are the small ones. Nail holes, anchor holes, the screws left behind by a mount. Each is small enough that a patch you can feel with a fingertip is a patch an inspector can see. One drag each, and you are on to the next wall instead of coming back for a second coat.

Know what it is not for. It fills holes, it does not bridge them. Anything big enough that nothing is left behind it to hold the fill, a doorknob punched through the drywall, needs a backing patch first. No filler pulled flat will save you there.

The other thing people get wrong is the rim. If torn paper is standing proud around the hole, the blade rides on the paper instead of the wall and leaves a low spot. Press that ragged edge down first. The pass only comes out flat if the surface it rides on is flat.

On a smooth painted wall that is the difference between repaired and never noticed. On a textured one it is a flat spot on a bumpy wall.