Going to be overly honest here. Wrenched and managed bike shops since 1981. Seen it all. Internal cable and hose routing is a labor booster as we do charge more to do the internal stuff vs. external stuff. The current craze with routing through the bars and stem is a total pia, but once we get good at it and figure out the tricks to do it quickly (if that ever happens, thus far it ain't looking good) we will then reap the rewards of this routing.
Before I retired from the biz I left management and went back to wrenching and it took a couple dozen bikes to figure out some tricks to routing hoses and cables inside a frame. This is when the extra time paid off in labor dollars. What we billed for 30 minutes became 15 minute jobs. In a day that can add up provided the shop is a higher volume shop.
Keep in mind not all frames, even from the same maker and same model, are created equal. Some routing goes smooth, other routing does not. Especially on carbon frames where there are scraps and crevices inside the frame tubes that catch things as they pass thru.