As permission inheritance doesn't work with reader accounts like it does with team account you have to check off ALL of the categories and multiple layers of sub categories you want them to have access to.
If this is hundreds of categories this takes an extremely long time, and is actually broken if you try to select more than 45 categories at one (I have a support ticket in for this).
It would literally save hours if we either had a check box for select all and then just uncheck the categories we don't want them to have access to or we could click the first box then hold shift and click the last box.
Preferably child permission inheritance would be preferable so we wouldn't have this issue to begin with but if we do have to check these off manually, especially if down the line new categories are made and we have to go into each reader and modify their permissions an easier and quicker way of selecting nearly all would be preferred