The router jig thing is real but here's the part nobody brings up. It's not the cutting that gets faster, it's the thinking. With a jig you spend half your time setting the thing up, checking it twice, praying it doesn't shift on you. So your brain never gets into a rhythm. Freehand or a straight edge and a saw, you just mark your lines and go. The speed comes from not stopping every 30 seconds to fuss with clamps and bushings. Most guys never notice because they learned on the jig and never tried it any other way.