I dont generally measure by speed anymore at all.
When I was a commercial superintendent I trimmed tract style specs on the side, very low sq ft price. My partner and I trimmed a house a day on a regular basis, 1400-2000 ft. Sometimes the day was 9 or 10 hours and sometimes it was 16. Sometimes we had to go back on Sunday. No window casings, just sill and sash, crappy stationary shelves in the pantry and closets. We even set pre fab cabinets by the box. We usually had to cut back masonite on the stained concrete to run base, too.
Made anywhere from 350-600 a house a peice. By no means the most ive ever made in a day as a GC, but 350 was nice little bump in pay as an employee. Insurance was less than 1200 a year.
Completely different skill set from custom trim, but just another skill set in the tool box.