Sleep is not rigid on primal.....if you eliminate modern lighting & distractions, not to mention work obligations I am sure you will find your natural sleep pattern. I know mine tends to be sleep 4-5ish hours wake for 1.5ish, sleep 2 ish with a long nap in the afternoon. Unfortunately not terribly friendly to the working world.
The rigid part is encouraging you to actually get restful sleep as so many do not.
The daylight driven sleep also prevents a seasonal problem for me. Did Grok really live this far north? In the winter I could not possibly sleep that much so that would be a lot of awake downtime. In the summer, I could not possibly sleep that little. I almost always need to nap in the summer because nighttime is so short
MTA: because it is rare I dont have more to say
"When I got too tired to run anymore I just pretended I wasnt tired and kept running anyway" - my daughter Age 7