Some projects are simply too small to get allocated more than one developer. However, small projects are not necessarily trivial and most of the time can hugely benefit from having an experienced Engineer to deliver them.
The most obvious benefit is the cost. Inexperience is expensive even if the developer charges substantially less for their time because it will simply take longer for the project to be delivered. I am very organised and prove to be very efficient through my always improving workflows. I automate as much as possible and use test-driven development to eliminate bugs from the start.