At 1+50 and 18º I develop for 20 minutes with incident metering at 200. That's for soft light. IMO that's its real speed for rich shadows.
For direct sun I use 1/250 f/8 1/2, with medium yellow filter, and develop for 15 minutes: that's incident metering at 50. (Film is 200. so 100 for the filter and 50 for the pull...)
Cheers,
Juan