I've been at both ends. Building apps as a solo developer, as well as fixing some bug or implementing a single feature correctly for clients. I think it requires being able to zoom in and zoom out along the stack of abstraction that constitutes a code base, as well as either focusing on the now or a much larger timeframe.

The higher level skills can be somewhat tested by asking the candidate how it would build some module and the variation that some factors would bring in (like closer deadline, no third party service,...)