I work at a company using something to this effect--when engineers get assigned projects they "own" them completely--from design and implementation to testing, deployment, verification, and bugs. We have a semi-formal tracking app with names attached to projects. There is never more than one person working on something. I think this instills a great culture of responsibility and accountability. It makes it very hard for someone to ride on others' coattails or not pull their weight, as you might get in a forced pair programming team, or a larger group.
Very interesting. Sounds like DRI (Directly Responsible Individual) at Apple. Are there any manager type roles (who does the assigning of projects to engineers)?
Maybe it's not an issue because it's a web company, and it doesn't take a rocket scientist to ramp up on any given module or system in the codebase.
Typical flow handled by one person is about 3 weeks from start of coding to live code, and then a couple more weeks on followup, stats, bugs, etc. After that it's just part of the codebase and others can end up working on it; but they'd probably talk to the original author to get up to speed.