Thanks Kurt and Walter, you confirmed my conclusion. The strang thing is that the footer approach was introduced in one of our daughter companies only a few years ago, being in WF4. A decision that will be reverted on Monday.
Crucial is the option "mass_property_calculate", an option I discovered only a week ago. When the default is "automatic", and there is an easy way to set a session to "by_request", there is no need for an extra feature in a footer.