Trying to study for interviews after a full workday and I'm basically useless by 9pm

Full-time job, plus supposedly two hours of prep every night, and by the time I open my laptop after dinner I've got maybe 40 minutes of actual focus before my brain just stops absorbing anything. Tried mornings instead, tried weekends only, tried splitting it into 20-minute chunks. Nothing sticks for long. At this point I think the problem isn't the schedule, it's that I'm pretending I have more hours in a day than I do. How are people actually doing this while working full time?