Faster GC methods have shorter times but Kovats indexes of the compounds may be conserved if proper method translation is applied.
Temperatures of the temperature program stay the same, but ramps and times change when using a smaller column or faster carrier gas.  
If column dimensions Length×diameter×film are divided by 2 and gas velocity is doubled by using H2 in place of Helium, the hold times must be divided by 4 and the ramps must be multiplied by 4 to keep the same index and the same retention temperature for the same compound analyzed. Method translation rules are incorporated in some chromatography data systems.