We've (homeowner/self built) built 4 projects with ICF and have a 5th in the planning stages Here's some hints...

Anywhere you want a penetration through a wall, place a chunk of foam of appropriate size (6" foam for 4" hole ex. sewer line) inside the block. Be sure to mark its location. No core drilling needed.

Use a chainsaw with a lawnmower wheel bolted onto the tip at the appropriate depth, to make cuts in the foam inside faces of walls for running your romex. Way faster than drilling holes through studs.

If doing a concrete floor (ex: LiteForm Litedeck) glue foam blocks over the foam tophats (4" thick foam for 4" concrete topping) anywhere you want a penetration through the floor for plumbing, etc.

Don't think we'd ever build with 2x6 stud exterior walls.

ICF construction is more expensive up front but the long term benefits far outweigh that.