If we want to look for insights from Keynesian economic thought, we should be wary of two simplifications. First is the idea that stimulus is about spending money, in any way possible, regardless of what it is spent on. Second is that public investment should occur only during recessions to provide a "kick-start," and then be removed.
A close reading of Keynes's writings reveals that he was concerned with industrial structure, and encouraged spending in strategic sectors. He also favoured sustained public investment to provide full employment and stabilize the economy against the inherent instability of financial markets.
In 1938, Keynes advised then-US president Roosevelt to prioritize investments in working class housing because the sector offered large and continuing scale of potential demand, wide geographical distribution of this demand, and because the sources of finance were largely independent of the stock exchanges. This advice for public sector spending was bolstered by Roosevelt's creation of new institutions to facilitate loans for mortgages, rural electrification, and manufacturing.
These policies ushered in a post-war "golden age," when the main trajectory for demand, investment, and innovation was defined by technologies such as the automobile, and new appliances in suburban houses. The Cold War introduced missions for government-led innovations in areas like space exploration that reverberated through the domestic economy.
The lesson we can take from history is that if we limit government action to a quick-hit stimulus that is quickly removed, we will not have a durable recovery. We need to find a socially useful mission that can direct public and private investment and innovation in the way suburbanization and the Cold War did in the 20th century.