This idea has been used for Yom Tov bonuses for either Kollel Yungeleit or melamdim, I don’t recall. Some storekeepers that accepted it grew frustrated quickly. They had to use it on Sale items, essentially losing money.
And the whole “redemption” process can get messy very quickly if the schools drag their feet with payment. We are talking schools that are likely in dire financial straits to begin with, and they may think of it as an extended payroll loan, hoping that by the time the cash is due the (tuition/Tzeddakah) funds will have become available.