process for flying lead harness?

if i purchase a flying lead harness with a prepinned ecu connector that has extensively color coded wires does it make any sense to use this instead of rope to do the initial routing and branching using small tie wraps to id branch points? In this scenario i would assign ecu pins and mark with painters tape the function of the wires. Without any connectors in place temporarily "installing" this in the vehicle should be very easy

I have made "fitment" harnesses for my customers, with just one wire for each sensor connector, labeled with tape. I instruct them to lay the wires in the car as they want, tape / wire tie them together, and put a piece of tape where each connector should go. When I get the figment harness back, I measure the distances, and bundles and create a layout document. Then I can design / build the harness with spliced power / grounds, shields, etc as needed.

It does work.