The PCT framework provides a possibility to prosecute a patent application in centralized proceedings for up to 152 PCT member states (as of June 2019). Although the PCT procedure is a bit more expensive upfront compared to national proceedings, the advantage of a PCT application is that it initially provides the option to protect an invention in all PCT member states and allows postponing the final decision with regards to those countries where finally a patent is pursued. This decision becomes due only 30 months after the earliest filing date of the invention.
Therefore, the PCT system provides a powerful option for protecting inventions of high strategic relevance but having a high technical risk at the same time. If such an invention finally turns out to be impracticable or unprofitable, you can save cost by reducing the number of countries where you actually enter into the national phase to pursue a patent.
That is, the PCT proceedings may be a useful option for software innovations where there are alternative, competitive technological approaches at the time of filing and it is not yet clear which approach will finally prevail. This makes sense at least in those cases where the expected life cycle of the technology is exceeding the duration of the “stretched” PCT procedure.