Temperature coefficient of copper is about 3930 parts per million per degree C
The trace will get stetched as the board changes temperature about 17ppm per degree.
Any flex in the board will also impart a larger ppm error (strain gauge effect)
A given plated pcb blank has tolerances on its plating thickness, purity and plating thickness consistancy
Etching is a very uncontrolled process for perfect traces, zoom in far enough and its bumpy and uneven in all kinds of fun ways,
In short, It would only be "accurate" at a very specific temperature, with no external force on the PCB, and you would not get a say in what value that is, just roughly where it sits,
If you want a precise value, easiest way is to buy some constantan wire, use that for most of your resistance value, and your within 40 parts per million, or manganin wire for within 20 parts per million, if you where serious, you could roughly use calculated lengths of the 2 to trim down the ppm to near nothing, then trim the length to get the ohms where you want it,
In some old equiptment this was wound around a bakelight like form card, and in 1 refurbed unit literally around cardboard, to get a very precise custom resistance value. leaving the only issue being measuring the thing,