If this was a response to write speeds they meant the speed at which data can be written to the disc, not the time ot takes to build the disc. Read/Write speeds are a standard measure used to tell whether something would be efficient to use. For example one could say storing an OS on a DVD and booting would be dumb because it would run extremely slow, where as the read speed for playing music or a movie off it wouldn’t be an issue as it doesn’t need higher performance for such.