This is to be used in conjunction with TS Config List which controls global approval enablement. There may be some projects that are exempt from the global approval policy. It is not practical to keep changing resource TS Config Lists each time they post time/expenses to a project.
Having a TS & ES approval bool fields on Project Header would allow for greater control over a variety of agreements across projects where different from the global setup in TS Config List. Reduce admin as removing need to go into each resource involved and assigning/reassigning TS Config.