Even if an idea is low in its maturity, you should always start in high fidelity.
It’s been a staple on our Design team to jump into high fidelity as soon as possible. There are so many elements of design which affect the experience, that to ignore them early on undermines the purpose of rendering it out in the first place.
This doesn’t discount the need for sketching and working through flow and business rules. However, there is such a radical departure from the confines of a sketch to placing actual pixels of actual color in an actual canvas that much of the emotional connection of the expereince is never explored until it is too late to use them effectively.
Color, Scale, Position, Contrast, Typography, Photography, Illustration, Voice. Mastering the use of these elements is core to delivering a complete experience design.
When we think of what affects an experience, we’re not only thinking about the efficiency of solving the customer’s problem, we’re also considering how the fundamentals of design deliver that solution effectively.