A lot of people and polls say Hillary is going to win, but in all history, there's only been one time that a presidential candidate was able to win a third term for their party. There are several other reasons why she's more of a longshot than people think she is, but I won't get into them here..
Not totally sure if I understand your post but if you check this list you will see there were plenty of times a party had a 3rd and more term consecutively:
[TABLE="width: 100%"]
[TR]
[TH]President[/TH]
[TH]Party[/TH]
[TH]Term as President[/TH]
[TH]Vice-President[/TH]
[/TR]
[TR]
[TD]1.
George Washington (1732-1799)[/TD]
[TD]None, Federalist[/TD]
[TD]1789-1797[/TD]
[TD]
John Adams[/TD]
[/TR]
[TR]
[TD]2.
John Adams (1735-1826)[/TD]
[TD]Federalist[/TD]
[TD]1797-1801[/TD]
[TD]
Thomas Jefferson[/TD]
[/TR]
[TR]
[TD]3.
Thomas Jefferson (1743-1826)[/TD]
[TD]Democratic-Republican[/TD]
[TD]1801-1809[/TD]
[TD]Aaron Burr, George Clinton[/TD]
[/TR]
[TR]
[TD]4.
James Madison (1751-1836)[/TD]
[TD]Democratic-Republican[/TD]
[TD]1809-1817[/TD]
[TD]George Clinton, Elbridge Gerry[/TD]
[/TR]
[TR]
[TD]5. James Monroe (1758-1831)[/TD]
[TD]Democratic-Republican[/TD]
[TD]1817-1825[/TD]
[TD]Daniel Tompkins[/TD]
[/TR]
[TR]
[TD]6.
John Quincy Adams (1767-1848)[/TD]
[TD]Democratic-Republican[/TD]
[TD]1825-1829[/TD]
[TD]John Calhoun[/TD]
[/TR]
[TR]
[TD]7. Andrew Jackson (1767-1845)[/TD]
[TD]Democrat[/TD]
[TD]1829-1837[/TD]
[TD]John Calhoun, Martin van Buren[/TD]
[/TR]
[TR]
[TD]8. Martin van Buren (1782-1862)[/TD]
[TD]Democrat[/TD]
[TD]1837-1841[/TD]
[TD]Richard Johnson[/TD]
[/TR]
[TR]
[TD]9. William H. Harrison (1773-1841)[/TD]
[TD]Whig[/TD]
[TD]1841[/TD]
[TD]John Tyler[/TD]
[/TR]
[TR]
[TD]10. John Tyler (1790-1862)[/TD]
[TD]Whig[/TD]
[TD]1841-1845[/TD]
[TD]
.[/TD]
[/TR]
[TR]
[TD]11. James K. Polk (1795-1849)[/TD]
[TD]Democrat[/TD]
[TD]1845-1849[/TD]
[TD]George Dallas[/TD]
[/TR]
[TR]
[TD]12. Zachary Taylor (1784-1850)[/TD]
[TD]Whig[/TD]
[TD]1849-1850[/TD]
[TD]Millard Fillmore[/TD]
[/TR]
[TR]
[TD]13. Millard Fillmore (1800-1874)[/TD]
[TD]Whig[/TD]
[TD]1850-1853[/TD]
[TD]
.[/TD]
[/TR]
[TR]
[TD]14. Franklin Pierce (1804-1869)[/TD]
[TD]Democrat[/TD]
[TD]1853-1857[/TD]
[TD]William King[/TD]
[/TR]
[TR]
[TD]15. James Buchanan (1791-1868)[/TD]
[TD]Democrat[/TD]
[TD]1857-1861[/TD]
[TD]John Breckinridge[/TD]
[/TR]
[TR]
[TD]16.
Abraham Lincoln (1809-1865)[/TD]
[TD]Republican[/TD]
[TD]1861-1865[/TD]
[TD]Hannibal Hamlin, Andrew Johnson[/TD]
[/TR]
[TR]
[TD]17. Andrew Johnson (1808-1875)[/TD]
[TD]National Union[/TD]
[TD]1865-1869[/TD]
[TD]
.[/TD]
[/TR]
[TR]
[TD]18. Ulysses S. Grant (1822-1885)[/TD]
[TD]Republican[/TD]
[TD]1869-1877[/TD]
[TD]Schuyler Colfax[/TD]
[/TR]
[TR]
[TD]19. Rutherford Hayes (1822-1893)[/TD]
[TD]Republican[/TD]
[TD]1877-1881[/TD]
[TD]William Wheeler[/TD]
[/TR]
[TR]
[TD]20. James Garfield (1831-1881)[/TD]
[TD]Republican[/TD]
[TD]1881[/TD]
[TD]Chester Arthur[/TD]
[/TR]
[TR]
[TD]21. Chester Arthur (1829-1886)[/TD]
[TD]Republican[/TD]
[TD]1881-1885[/TD]
[TD]
.[/TD]
[/TR]
[TR]
[TD]22. Grover Cleveland (1837-1908)[/TD]
[TD]Democrat[/TD]
[TD]1885-1889[/TD]
[TD]Thomas Hendriks[/TD]
[/TR]
[TR]
[TD]23. Benjamin Harrison (1833-1901)[/TD]
[TD]Republican[/TD]
[TD]1889-1893[/TD]
[TD]Levi Morton[/TD]
[/TR]
[TR]
[TD]24. Grover Cleveland (1837-1908)[/TD]
[TD]Democrat[/TD]
[TD]1893-1897[/TD]
[TD]Adlai Stevenson[/TD]
[/TR]
[TR]
[TD]25. William McKinley (1843-1901)[/TD]
[TD]Republican[/TD]
[TD]1897-1901[/TD]
[TD]Garret Hobart, Theodore Roosevelt[/TD]
[/TR]
[TR]
[TD]26. Theodore Roosevelt (1858-1919)[/TD]
[TD]Republican[/TD]
[TD]1901-1909[/TD]
[TD]Charles Fairbanks[/TD]
[/TR]
[TR]
[TD]27. William Taft (1857-1930)[/TD]
[TD]Republican[/TD]
[TD]1909-1913[/TD]
[TD]James Sherman[/TD]
[/TR]
[TR]
[TD]28. Woodrow Wilson (1856-1924)[/TD]
[TD]Democrat[/TD]
[TD]1913-1921[/TD]
[TD]Thomas Marshall[/TD]
[/TR]
[TR]
[TD]29. Warren Harding (1865-1923)[/TD]
[TD]Republican[/TD]
[TD]1921-1923[/TD]
[TD]Calvin Coolidge[/TD]
[/TR]
[TR]
[TD]30. Calvin Coolidge (1872-1933)[/TD]
[TD]Republican[/TD]
[TD]1923-1929[/TD]
[TD]Charles Dawes[/TD]
[/TR]
[TR]
[TD]31. Herbert C. Hoover (1874-1964)[/TD]
[TD]Republican[/TD]
[TD]1929-1933[/TD]
[TD]Charles Curtis[/TD]
[/TR]
[TR]
[TD]32.
Franklin Delano Roosevelt (1882-1945)[/TD]
[TD]Democrat[/TD]
[TD]1933-1945[/TD]
[TD]John Garner, Henry Wallace, Harry S. Truman[/TD]
[/TR]
[TR]
[TD]33. Harry S Truman (1884-1972)[/TD]
[TD]Democrat[/TD]
[TD]1945-1953[/TD]
[TD]Alben Barkley[/TD]
[/TR]
[TR]
[TD]34.
Dwight David Eisenhower (1890-1969)[/TD]
[TD]Republican[/TD]
[TD]1953-1961[/TD]
[TD]Richard Milhous Nixon[/TD]
[/TR]
[TR]
[TD]35.
John Fitzgerald Kennedy (1917-1963)[/TD]
[TD]Democrat[/TD]
[TD]1961-1963[/TD]
[TD]Lyndon Johnson[/TD]
[/TR]
[TR]
[TD]36. Lyndon Baines Johnson (1908-1973)[/TD]
[TD]Democrat[/TD]
[TD]1963-1969[/TD]
[TD]Hubert Humphrey[/TD]
[/TR]
[TR]
[TD]37. Richard Milhous Nixon (1913-1994)[/TD]
[TD]Republican[/TD]
[TD]1969-1974[/TD]
[TD]Spiro Agnew,
Gerald R. Ford[/TD]
[/TR]
[TR]
[TD]38.
Gerald R. Ford (1913- 2006)[/TD]
[TD]Republican[/TD]
[TD]1974-1977[/TD]
[TD]Nelson Rockefeller[/TD]
[/TR]
[TR]
[TD]39. James (Jimmy) Earl Carter, Jr. (1924- )[/TD]
[TD]Democrat[/TD]
[TD]1977-1981[/TD]
[TD]Walter Mondale[/TD]
[/TR]
[TR]
[TD]40.
Ronald Wilson Reagan (1911- 2004)[/TD]
[TD]Republican[/TD]
[TD]1981-1989[/TD]
[TD]George H. W. Bush[/TD]
[/TR]
[TR]
[TD]41. George H. W. Bush (1924- )[/TD]
[TD]Republican[/TD]
[TD]1989-1993[/TD]
[TD]James Danforth (Dan) Quayle[/TD]
[/TR]
[TR]
[TD]42. William (Bill) Jefferson Clinton (1946- )[/TD]
[TD]Democrat[/TD]
[TD]1993-2001[/TD]
[TD]Al Gore[/TD]
[/TR]
[TR]
[TD]43.
George W. Bush (1946- )[/TD]
[TD]Republican[/TD]
[TD]2001-2009[/TD]
[TD]Richard Cheney[/TD]
[/TR]
[TR]
[TD]44.
Barack Obama (1961- )[/TD]
[TD]Democrat[/TD]
[TD]2009-[/TD]
[TD]Joseph Biden[/TD]
[/TR]
[/TABLE]