For small banks, it's found in GLB:
> > SEC. 809. SMALL BANK REGULATORY RELIEF.
(a) IN GENERAL- Except as provided in subsections (b) and (c), any regulated financial institution with aggregate assets of not more than $250,000,000 shall be subject to routine examination under this title--
(1) not more than once every 60 months for an institution that has achieved a rating of `outstanding record of meeting community credit needs' at its most recent examination under section 804;
(2) not more than once every 48 months for an institution that has received a rating of `satisfactory record of meeting community credit needs' at its most recent examination under section 804;
and(3) as deemed necessary by the appropriate Federal financial supervisory agency, for an institution that has received a rating of less than `satisfactory record of meeting community credit needs' at its most recent examination under section 804.