Today I ran wiring for the right wing. I found that I had plenty of space for the standard wiring harnesses, plus several spare 18 and 22 gauge wires that I ran for future use. The wiring runs were for the AutoPilot, Trim Servo, and the wing lighting.
I have a label printer that will print on heat shrink, so I can easily label wires. This makes it so easy!
Many builders run conduit through the wings, to make it easier to run cable in the future. At this stage my plan is to just install several spare wires for future use, and not install conduit. Conduit would require drilling a new set of holes through each rib. It’s not really necessary, as I can reach each rib via the access panels anyway.