@williamatics There are some engineering flow/stress simulations that don’t necessarily need to take size into account, but proportions will mater quite a bit. They take the form of converting things to dimensionless values that you can scale to small objects so that you can test a principle on something like a Freight Plane in a small wind tunnel that only fits something 2 feet tall. There are a lot of practical simulation scenarios where size probably does matter too though.
All in all I would agree that real world units help you to keep track of proportions, especially when making objects that interact with people, like in @jlampel ‘s course on the mesh modeling bootcamp. He talks about this during the modeling the pistol. The handle and trigger are where the hand would interact so they should be able to be size-proportionate for a hand to be able to grab them. Real world units helps with this.
