The FED wouldn’t have been able to target N-gDp during the Great Inflation unless they changed their operating procedure. The banksters simply usurped the trading desks’ “open market power”.
The effect of tying open market policy to a fed funds bracket was to supply additional (& excessive) legal reserves to the banking system when loan demand increased.
Since the member banks had no excess reserves of significance, the banks had to acquire additional reserves to support the expansion of deposits, resulting from their loan expansion. If they used the Fed Funds bracket (which was typical), the rate was bid up & the Fed responded by putting though buy orders, reserves were increased, & soon a multiple volume of money was created on the basis of any given increase in legal reserves.