That makes sense for debts, but how do you handle people who immediately blow their monthly UBI payment and don't have anything left over for food or rent? At least with food stamps, you kind of have to use it on food.
Weekly or even daily payments would cover part of that. You know the amount that should be added to an account each day pretty easily, since it's the same for everyone. If they waste it and still can't afford food or rent, well, at some point you have to make that their problem.