I have a 9 hours light cycle.
Actinics 5pm to 2am.
Full lights: 6:45pm to 1:15am
In the summer, I shorten the full light cycle by an hour to help reduce heat issues, but keep actinics the same.
I used to run my full lights for 10hours and more, but found I got better and thicker sps growth when I shortened the full light cycle to the 7-8hr range.