Hello, I do something similar to what Aster wrote.
I initial used both the information from the conjuring and the CH description. A few months ago I was able to use a tarot deck to learn more about my team and their individual likes and capabilities, more so outside the descriptions. I reworked it to (under my house rules) to make sure I give/request tasks within those capabilities. So there is some play outside of the descriptions, but not too far. My Keep totals about 40 (I learned of trials regarding immortals and I think I am going through them so they not counted here, with all due respect). Everyone is tasked with someone else in some form. Protection - I have asked individual spirits to look over individual loved one, but they can rotate. I have at least one task that is meant to benefit the Keep directly.
Otherwise, I ask them for one off support like casting spells or support with life's challenges. They seem to appreciate receiving spells as a Thank yous (I give more than that because they all deserve love). As I learn how to communicate better this structure may change. As long as they follow the House Rules they can attend to things and come and go as they please.
No more than 3 assigned tasks at a time (4 in an emergency).
We review progress once a week, adjust tasks if necessary.
All tasked have 2 or more assigned
At least 1 task is meant to benefit the Keep directly (outside of my needs/desires)
Everyone must take care of themselves first before working on any tasks.