The dimensional accuracy is important if you want to build parts, which have to fit together precisely. Shrinking of the polymer plays also an important role at this part. To handle this issue, you can set the extrusion multiplier or the extrusion width for a perfect result. Also the first layer height or a constant dimensional error of the printer could be a problem.
For dimensional accuracy it is necessary to set the first layer correctly. Figure it out by changing in small steps. If it is set lower than the first layer should be, too much plastic will come out of the nozzle and this error will continue to the next 10-20 layers. The result will be oversized layers.
For dimensional accuracy the amount of extruded material is a limiting factor for success. Start at an extrusion multiplier from 1, and if too much plastic will be extruded, decease it in 5% steps. It depends on which material you use, which printer and on the nozzle diameter, how easy the material flows.