This year will equal the longest time between premiership deciders. 1900/01 was because a third round of matches was added (which was widely unpopular). With of course, 2000 finishing three weeks earlier due to the Olympic Games.
Longest:
1900 to 1901 - 392 days
2000 to 2001 - 392 days
1909 to 1910 - 385 days
1920 to 1921 - 385 days
Shortest:
1901 to 1902 - 336 days
1999 to 2000 - 343 days
1919 to 1920 - 346 days