How long does it take to process a Non-B visa and COE in the US?

In response to inquiries about the processing time for a Non-B visa in the US, some commenters mentioned that it generally takes around 15 working days for both the visa and the Certificate of Entry (COE). However, others noted that the process can be faster, suggesting that visas and COEs can be issued almost immediately if all documentation is in order. One person shared their experience of a longer processing time, taking up to five weeks, which prompted questions about the method of application.