"Practically speaking, the tax rate should vary and not be a fixed value, but here is how it should work."
Perhaps you meant to say, "impractically speaking.." Politics would never act so precisely, so this idea is utterly IMPRACTICAL.
Furthermore, it is wrong. The function of tax rates is not to regulate the economy. It is to provide resources for legitimate government functions: defense and justice.
One of our problems is that tax money is used for all sorts of transfer payments, breaking the nexus between provider and spender, and thereby irrationalizing the deployment of resources. Government expenditures often make certain problems worse, as in the field of education, where government control has diluted what is taught, and has acted to drive up college expenses. It has encouraged a whole industry engaged in keeping young people out of the word of adult responsibility. Much of our "spoiled child" culture is driven by this system.
Anyway, the Laffer curve does work. It is a mixed blessing, though, if it gives the government more money.
No need to shout, we're right here. The idea is not only practical, but it's also what's practiced.
This procedure for taxing booms and spending on slumps is what's written into the tax code so nobody has to wait for the new budget to kick in. The idea of income tax brakets is to up the tax rate automatically with increasing incomes. "Luxury" taxes is another angle. It's the standard model that works pretty well.
The doom'n'gloom press makes it look like the end of the world when some goofy factory lays off a dozen workers, but I guess since the press gets paid to wet their pants any chance they get then they'll keep it up until we stop reading their drivel.