John Lawler's writing on time-banking (paraphrased here from public summaries of the work titled 'Time Is Money') frames non-monetary exchange — hours of skilled labour, mentoring, caregiving — as a parallel ledger that families have always run alongside their financial one. The interesting claim is not that one replaces the other; it is that ignoring the non-monetary ledger leads families to mis-price the financial one.
For a trustee, the practical use is in pricing soft commitments around a loan. A profit-sharing arrangement with a young entrepreneur in the family is rarely about the basis points; it is about the trustee's hours of mentoring. A qard-hasan-style benevolent loan to a beneficiary in hardship is rarely about the interest forgone; it is about the family time that buys the borrower a runway.
Naming the non-monetary side of the ledger does not require a parallel accounting system. It requires a sentence in the loan memo. That sentence is what future trustees and beneficiaries will read when they ask why the deal was structured the way it was.