An exponential back-off implementation I used somewhere; probably room for improvement, but it works good enough. (updated thanks to Anders Melander)

TryGetLocationLockWithExponentialBackOff.pas

function TryGetLocationLockWithExponentialBackOff: Boolean;
const
  cBase = 2;
  cMaxWaitMilliSeconds = 1500;
var
  lWaitMilliSeconds: integer;
begin
  Result := True;
  lWaitMilliSeconds := cBase;
  while (not TryGetLocationLock) do
  begin
  if (lWaitMilliSeconds > cMaxWaitMilliSeconds) then
    Exit(False);
    Sleep(lWaitMilliSeconds);
    Inc(lWaitMilliSeconds, lWaitMilliSeconds);
  end;
end;

TryGetLocationLockWithExponentialBackOff_Old.pas

    function TryGetLocationLockWithExponentialBackOff: Boolean;
    const
        cBase = 2;
        cMaxWaitMilliSeconds = 1500;
    var
        lIteration: Integer;
        lWaitMilliSeconds: Single;
    begin
        lIteration := 1;
        lWaitMilliSeconds := 0;
        while lWaitMilliSeconds < cMaxWaitMilliSeconds do
        begin
          Result := TryGetLocationLock;
          if Result then
            Exit;
          lWaitMilliSeconds := IntPower(cBase, lIteration);
          Inc(lIteration);
          Sleep(Round(lWaitMilliSeconds));
        end;
        Result := TryGetLocationLock;
    end;