A good lead developer should help you grow, partially by selecting problems and partly by providing more/less structure. E.g. I might tell a junior developer to

A good lead developer should help you grow, partially by selecting problems and partly by providing more/less structure. E.g. I might tell a junior developer to implement the design on the whiteboard and provide multiple rounds of code review, because just getting a complex implementation right is plenty challenging; for a more-senior colleague, I'm much more likely to throw him/her at a complex problem and I'll provide a few "you could have improved <X> by <Y>", possibly afterwards.