"usually"?

Fact check: pants on fire.

Until Reagan, both Democrats and Republicans were relatively fiscally responsible, not racking up too much debt relative to GDP. Part of the reason for that is the US economy was growing at a meteoric rate being one of the only industrialized countries not to be destroyed in World war II, and with a quickly growing economy it was a lot easier to keep spending under revenue because revenue was increasing every year. The debt number rarely dropped, but inflation saw the national debt relative to GDP shrink. Reagan tripled the national debt to get out of the stagflation crisis of the 1970s (among other things, he was also fighting the Cold war), bush 1 spent money at a high rate too. Clinton almost balanced the budget thanks in part to the huge economic boom from the dot com bubble. Bush 2 doubled the national debt due to increased military spending on two wars that were part of the war on terror, security spending, and since then there's been no winning move, with Obama doubling the national debt, trump almost increasing it as much in 4 years (which included the pandemic to be fair) as Obama did in 8, Biden ran it up a bunch, and Trump is keeping up the tradition with very little in sight in terms of an exit strategy for anyone at this point.

Even the post-WWII fiscal restraint was a bit of a mirage. The Bretton woods system meet the US dollar the reserve currency of the world, would you allowed them to play some games when issuing currency that allowed the federal debt to State relatively small. If everything was kosher, the stagflation crisis of the 1970s never would have happened.

While there have been times in the past that the United States has paid off its debts, such as after the revolutionary war and after the civil war, they would have been so long ago that even the definitions of parties would be fundamentally different. For the most part, other than immediately following World war II where demobilization allowed for the sale of a bunch of military hardware, nominal debt value almost never dropped, and even inflation adjusted would tend to stay around the same spot until stagflation broke everything.