Did you thoroughly read through the linked sources?

Because in source number 5, it mentions that some fraction of Class III submissions are cleared through the 510(k) process and not exclusively through the PMA process.

> In 2007, Congress asked the Government Accountability Office (GAO) to review the 510(k) process. The resulting 2009 GAO report described the 510(k) process as less stringent, faster, and less expensive than the PMA process and concluded that 66% of Class III submissions cleared through the 510(k) process in recent years were “implantable, life sustaining, or of significant risk,”