Anyone who quotes a firm price before seeing the job is guessing, and the guess is built to protect them rather than you. What follows is what actually moves the number, so you can judge any quote you are given, including ours.
The largest factor is time on site. A flat-pack chest of drawers and a six-door wardrobe are the same category of work and nowhere near the same job. Where a piece has many small drawers, each with its own runners, the part count matters far more than the size of the finished item.
Travel, parking and setting up happen once per visit whether we do one job or six. That fixed part is why a single small task is poor value and a list is good value. If you have three things, get all three done together.
For anything that gets fixed to a wall, the construction decides the work. Drywall with studs where you need them is straightforward. Brick, tile, plaster over block, or a mount that has to span an awkward gap all take longer and need different fixings.
A third-floor apartment with no elevator, a narrow stair turn, or a room that has to be cleared before work can start all add time. None of it is complicated, but it is real and it is better priced in than discovered.
Taking the packaging away is included. So is cleaning up. The estimate is free, and the price agreed before work starts is the price paid: if we underestimated, that is our problem, not a change order.
Send photos and the list. That is genuinely all it takes, and you will get a figure rather than a range.
Small, predictable work is simplest priced by the job, because the number is known before anyone starts. Open ended work, where what is behind the wall decides how long it takes, is more honestly priced by time. Either is fine. What matters is being told which one you are getting, before rather than after.
A quote worth trusting says what is included, what would change it, and what happens if the work runs longer than expected. A bare number tells you nothing you can check, and a wide range usually means nobody looked at the photos.
Most jobs need a handful of fixings and that is not where the money goes. Materials start to matter when the right anchor for the wall is not the one that came in the box, or when making good needs filler and paint rather than a screw.
Where a part is missing, or the wall turns out to be something other than it looked, the choice is to improvise or to come back. Improvising is how a bracket ends up in drywall instead of framing. Coming back costs a second visit, and that is the real reason the photos get asked for in advance.