Imagine that you need to flash hundreds of microcontrolelr chips. One way is to do this one by one, but this can be exhausting task and plus inefficient. If you use standard ISP adapter your boards has to be with ISP headers soldered on- this also rises overall cost. So how to do this faster and efficient. If you have a CNC platform lying around, it may be fairly easy.
Pleasantsoftware shared his rig where he managed to set up an automated solution of AVR flashing. He needed to flash several hundred of AVRs so building this rig seemed quite reasonable. On his boards he used special programming connector which sits on SMD chip directly to ISP and power pins. Assembled PCBs come in panels of 40. All he had to do is to build a programming connector holder which was 3D printed. He used his G-Code sender app to send position commands to CNC. Hex code and fuses are hard coded in to source since it is same for all batch. Single panel of 40 AVRs are flashed in 10-12 minutes. I doubt that this can be done manually and still be enthusiastic about this.