Maybe not as effective as the Federal Reserve System might think. At least not in the 1930s. In their latest NBER working paper, Charles Calomiris, Joseph Mason, and David Wheelock adopts a microeconomic approach to answering the question, "Did Doubling Reserve Requirements Cause the Recession of 1937-1938?" Their answer: no.
"[W]e find that despite being doubled, reserve requirements were not binding on bank reserve demand in 1936 and 1937, and therefore could not have produced a significant contraction in the money multiplier. To the extent that increases in reserve demand occurred from 1935 to 1937, they reflected fundamental changes in the determinants of reserve demand and not changes in reserve requirements."
It is already a growing consensus that reserve requirements are no longer that effective as it has become less binding for most banks. This is definitely one case where government intervention is unnecessary as the market (the banks) itself will try to change its reserve holdings to adapt to its changing environment, and hence subtly putting a safety net against bankruptcy.
Such safety net is, in the first place, what the Fed's reserve requirements are there for. So there's no need for government to put some redundancy in this case. On the other hand, the use of reserve requirements to control the money supply is again also unnecessary as the market inadvertently causes such policy tool to be non-binding.