there is a huge number of 24, 48 hours (and even longer) contests.
But there is and very small ones - with duration only one hour. One of this kind is Bulgarian LZ CW CLUB Contest. It will be held on October 25, from 18:00 till 19:00 UTC only 80 m band and every last Thursday of the month. Full rules are in http://web.orbitel.bg/lzcwc/ruleseng.html
Other short CW contest is Russian MiniTest. His rules are in http://minitest.narod.ru/polovenie.html
(In Russian, but if you do not understand this language, ask me, I will translate).
Do you know other short CW contests?
Let me know, please !
73 Sasho, LZ1FW