Alternative phrase to "Let your friends direct your movies"

Solution 1:

The concept of being the right person to start a project but the wrong one to pursue it is a socially awkward suggestion to make (but there is some good sense in it) as it ignores the person's original genius and focusses upon their failure.

The nearest I can think of is "Horses for courses". this is a common expression with a horse racing reference indicating that if you have several horses and you want to win a short race over hurdles, you do not choose a horse that is good at long distance races without hurdles.

This has a slightly different focus, and means that the person required for a task should be chosen with respect to their talents, rather than mere success in other fields, i.e. it does not suggest that the person should have been the originator of the idea or the first to do it.