If you look at the time of year these world cups took place the time between them are almost comparable.
wikipedia list
1975 (7 June - 21 June) England
1979 (9 June - 23 June) England
1983 (9 June - 25 June) England
1987 (8 October - 8 November) India, Pakistan
1992 (22 February - 25 March) Australia, NZ
1996 (14 February - 17 March) India, Pakistan, Sri Lanka
1999 (14 May - 20 June) England, Wales, Ireland, Scotland, Netherlands
2003 (9 February - 23 March) SA, Kenya, Zimbabwe
2007 (13 March - 28 April) WI
2011 (19 February - 2 April) India, Sri Lanka, Bangladesh
2015 (14 February - 29 March) Australia, NZ
As can be seen that the 1992 world cup was 4 years 3 months after the 1987 world cup. In Australia and NZ the best cricket weather is after the new year, so that is probablty why it appeared as 1992 and not late 1991.
Exactly 4 years later Sri Lanka held the world cup in 1996. If this was readjusted, again leaving only 3 years for them to host, which could have been too short
