The first few weeks of post-election transition planning for President-elect Donald Trump and Capitol Hill Republicans are heady times for semi-virtual reality. A new White House in partnership with Republican control of both houses of Congress and a substantial majority of state governors and legislatures tempts political imaginations to write boldly and broadly, as if on a clean slate.

In particular, six years of pent-up ambitions to repeal Obamacare and replace it with “something else” are reaching escapist velocities. Theories and game plans abound for how the repeal part of the mission should be executed rapidly.

Meanwhile, the replace complement lags further behind in gaining consensus on key elements, let alone surmounting daunting challenges of transitional timing and effective implementation.

Hence, the need for speed around the repeal track needs to be tempered by sufficient respect for the caution lights flashing ahead, as well as a longer range look around the corners and over the horizon.

First, some lessons of history. Most first years of new presidents, or even re-elected ones, involve overreaching claims of sweeping mandates that reach their perishable sell-by date far ahead of schedule. Enacting major legislative changes in the modern era, or even striking popular poses during campaigns, may put a political premium on rapid action over deliberative thought.

However, an ensuing round of clean-ups, corrections or crack-ups also is more of the predictable rule than an exception. See, for example, the Reagan tax cuts of 1981, Bush 41’s reverse lip reading of fiscal policy from 1989 to 1990, Bill Clinton’s 1993 health care plan, Bush 43’s Social Security reform plan of 2005, and the tortuous path of Obamacare from 2009 onward.

Where those once-lofty hopes and dreams ended up were in far different places than they began. And, unlike presidential candidate Trump’s thin record on Obamacare (“It’s bad, so we should get rid of it”), they at least involved far more discussion and development on the campaign trail. Most of the winning candidates even gained popular-vote pluralities!

Second, as in more serious warfare, no battle plan on Capitol Hill survives unchanged after the first shots are fired and casualties mount. Current speculation over Hill Republican plans to end Obamacare often presumes rapid adoption of a new budget resolution in January, quick agreement in the House and Senate on a limited budget reconciliation measure focused on repealing as much of Obamacare as is procedurally imaginable (i.e., limited to its aspects with fiscal effects), finessing of transitional chaos by smoothly phasing out old subsidies and rules with new ones within two years, and complete suppression of any defections or competing agendas within Republican ranks. As if!

Meanwhile, no detailed legislative language has been agreed upon and appeared in public (or even been drafted), no votes have been taken, and there’s no track record for how President Trump will handle his first tweet of disagreement on health policy with Congress. For some historical perspective, even unified and efficient sessions of Congress have had great difficulty in agreeing on any budget resolution, let alone within the regularly prescribed timetable of three to four months.

President Obama, even with a supermajority in the Senate in 2009, was barely able to drag the Affordable Care Act, in half-finished form, across the finish line after more than 14 months into his first term.

So, history will not begin anew on January 20, 2017, or even soon thereafter. The best efforts of House Republican leaders to jam through Obamacare repeal quickly, in hopes of leveraging their Better Way replacement draft into law later in the year, will face slowdowns in the Senate, as well as complications in how they deal with a host of questions, unresolved conflicts, interest group concerns, budgetary math barriers, and political resistance elsewhere. Meanwhile, the health policy debate will not operate inside a bubble, impervious to unexpected events internationally and across the economy.

But history also tells us that whenever a new governing majority, no matter how tenuous, stakes a major claim that it will, no matter what, effect significant policy changes, it usually manages to do so, no matter how desperate and prolonged the effort it takes to get something out the door and into law (even if not exactly in the manner and substance first promised). See, for example, the Medicare drug benefit passed (like a kidney stone) in 2003; the Medicare portions of the Balanced Budget Act of 1997, and, of course, the Affordable Care Act of 2010.

In such cases, political failure is not an option. But delay, obfuscation, redefinition, and exaggeration will be predictable rest stops along the way. Our political leaders probably can’t do much worse, but they certainly can try.