Most door projects in Gauteng and the Western Cape do not fail because someone picked the wrong timber. They fail because the service format was wrong from the start. A homeowner ordering two interior doors and a contractor fitting forty units across a townhouse block need very different arrangements, even when the doors themselves come from the same rack.
The first thing worth checking is who measures. If you measure your own opening and order a leaf, you carry the risk on the frame being out of square, the floor level, and the wall thickness. That is fine for a single bedroom door where you can adjust the architrave. It is not fine for a pivot unit, where the rough opening has to be set before screed and tile go down.
The second decision is supply only versus supply and install. Supply only suits a DIY customer with a level, a chisel and time on a Saturday. Supply and install makes more sense when the schedule runs across multiple units, when the frames need to be set into wet walls, or when the door hardware has to match across a whole house. Mixing the two on one project usually costs more than picking one.
Delivery lead times also shape the format. Standard 813mm and 914mm meranti leaves move quickly from stock. Custom widths, oak veneer and powder-coated aluminium pivot units are made to order, so they need to be sequenced against tiling and painting rather than ordered the week the painter arrives.
None of this is complicated, but it does need to be decided early. The format you choose sets the measuring responsibility, the installation sequence and the lead time, and those three things are much harder to change once the walls are closed up.
Related reading: service formats and supply options and how past clients handled their fit.