As long as you keep new borrowing below growth then you can do that indefinitely. The problem is when the next pandemic (or war) comes along you don't have much room to deal with it.
You can do the same with printing money, as long as you do it below growth you can do it indefinitely.
The problem always is that you can't stop and get off the tiger. No country can withstand the shock of a major cut in spending, because the population can't absorb the hit.
