Things are much different here then, many of the buildings I have done didn’t even have roof anchors.
Redirection is pretty much is standard generally via butterflying your working rope to your safety, always working with angles, you have to understand vector force.
When taking vector force into consideration having a 45 degree angle between each anchor point would effectively half the weight that each anchor point would bare, while on the extreme scale if you somehow were able to have anchor points at 170 degrees then each anchor point would take upon it 574% of the strain of the weight. So using angles is beneficial when rigging ropes to the direction you require when the anchor point doesn’t line up with the drop, even if its not needed that butterfly added to the rope would allow your main like to still be operational even if the anchor failed, as that extra knot becomes a backup.
Personally I would rather anchor( or at the VERY least back up) to a nice big chunk of structural steel.
