sun
For many things in Bonsai there really aren't any pat answers. A lot depends on many factors surrounding the tree(s), soil, size of pot and soil mix, etc, etc.
Perfect example:
I have a very large Fukien Tea-about 20+ years old, everything I read says '1-2 or a few hours of direct sunlight a day'--it's growing well in a courtyard where it gets 80% sun for about 10 hours a day. I'm in Vietnam, about 12 degrees above the equator and the sun is brutal for about 8 months a year so go figure. All of the trees get watered at least once a day sometimes twice, they also get misted heavily a few times a day, they also get 3-4 months of monsoon rains, almost every day, all day.
Bob