> More flights (its' virtue another discussion), more cars produced, more parties planned, food made, services rendered.
That would only be possible if we had previously been using the labour and capital to produce those things at less than 100% efficiency. That's not what happens. Businesses will always have been trying to operate as efficiently as possible. When demand increases they either have to increase prices or increase supply. Increasing prices will mean that someone else doesn't get the good or service. Increasing supply will mean employing extra labour or capital that would otherwise have been used elsewhere. Either way, spending money doesn't cause total productivity to increase.
(Unless of course the Fed screwed up and put us in a deflationary recession. In which case, yeah, extra spending would help. But that's only if they screwed up. Normally, they have already optimised the variable you're trying to adjust. Adjusting it away from the optimum will just cause them to push it back.)