The beauty of a $12m property is you can outsource the leg work to someone else for a percentage of the income - the time you spend on it is entirely up to you.
A single asset worth $12m would have some degree of on site management - operations/facilities manager p/t property/centre manager as a minimum - being a net lease, the tenants wear the management, maintenance and outgoing costs. Whether you outsource these functions is a business decision. Westfield, Mirvac, Stocklands keep the management in house where as many of the smaller players don't have the skill set or capacity to take on all of the compliance matters, leasing, strategy, tenancy mix, asset management, planning, property management functions, contract negotiations, finance etc which go hand in hand with managing the facility.