I think it's actually 5 minutes from Bathurst to Bloor-Yonge. I strongly suspect there are conservative operations for the Eglinton underground section as well (i.e. acceleration, braking, platform speed limits, dwell times).
I may be 100% wrong about not including red lights, but something doesn't add up. I calculated a simple model that is spot on with the average segment times for underground and surface. I included 30 sec for stationary time at each stop, but I didn't include red light time. The only way one can manage 23-25 km/h average speeds for the underground section is with some combo of slow acceleration and braking, as well as low platform speed limits and long dwell times. If acceleration is slow underground, then upping the top speed to 88 from 60 km/h would only save 2-4 seconds per segment i.e. virtually no difference in average speed.
For reference, Line 2 Bloor's average speed downtown is 26-27 km/h.
This is why expectations for Sunday should be tempered, Line 6 FW was consistently doing 50, 60+ minutes when it opened, slower than scheduled. It's now frequently in the mid 40s.