Advanced members especially if they have a kid, they have very dense days. Some yoga sessions can take more than a hour, so probably there are a lot of SS, do have even longer routine than 3 hours. Being a SS is like having a side job, and along with that, working for the JoS is like having a second side job, and than having a family with kids, is the 3rd side job. But I can only guess that HPHC and now HPS Lyida's full time job is being an SS. Or at least I could not imagine how could they go to work with so much other works.
As a beginner it can be enough even 30min-1hour, and than you go longer and longer STEP BY STEP, so you can adapt