Habits that only run on weekdays never fully settle, because every Monday asks you to restart something instead of continue it. Two loose days are enough to reset the momentum, so the week opens with friction that a small amount of Saturday effort would have prevented. Continuity is what makes a routine cheap to keep.

None of that means working through the weekend. Keep one light version of the thing, twenty minutes, the easiest part, enough that nothing has to be picked up cold. Rest properly around it and let Monday be a continuation rather than a beginning.