Being Bruce Wayne doesn’t take much time at all. Being a capital landlord just means barking a few orders and paying other people to actually work.
A boardroom meeting here, a fancy party there.
This was portrayed very well in the Nolan trilogy.
If anything he’s Batman or training/prepping to be batman 12+ hours a day, sleeping 6-8 or maintaining muscle would be next to impossible(if he is in fact supposed to be human), and the rest to being a billionaire CEO.