I received SS when my dad became disabled. We had a checking account set up, rather than a savings account. We had to account for everything we spent, but did not have to save any specific amount. We wrote checks for each individual thing, though I don't think we were required to - we did it just because it was easier to keep track of that way.
I'm not sure if you've checked this out but maybe it will be of help:
http://www.ssa.gov/pubs/10076.html
"First, you must make sure the beneficiary’s day-to-day needs for food and shelter are met. Then, the money can be used for any of the beneficiary’s medical and dental care that is not covered by health insurance, and for personal needs, such as clothing and recreation. If there is money left after you pay for the beneficiary’s needs, it must be saved, preferably in an interest-bearing account or U.S. Savings Bonds."