He didn't address it because, it's depended on place. Conventional economic wisdom is to pass tax cuts during down times to spur buying. If you pass a cut during a boom (possibly overheating the economy), and the market crashes, you are going to have issues. You can't double down with another cut. The result is a longer and more severe recession, approaching a depression. The reason why it's location specific, is because some nations will do what is necessary to pull themselves out of such; that would be by slashing govt spending. Many of the first world economies in Europe would do this. This would not happen in the United States. Milton Friedman explains it as:
"Suppose the government spends $400 billion, and raises $350 billion in funds labeled taxes. Who do you suppose pays for the $50 billion difference? The Tooth-Fairy? Hardly. You do."
So, it is reasonable to keep tax cuts in your back pocket until they are actually needed, because the potential downside is enormous.
So you told me to look him up, and then admit he doesn't address it?
You can't escape that little triangle on the suply and demand graph marking the inefficiency created by taxation. Reducing that inefficiency is a good thing, no matter when you do it. Markets might go through ups and downs, and the government might run budget deficits in the near term if there is a downturn in the economy (due to other factors, of which their can be many). But the economy will, on balance, be healthier than it would without the reduction in economic inefficiency. And that is basically what Friedman is saying in the quote you provided. The government will run a deficit which will then require some time of fix, or (gasp) patience.