To attain god people do a lot of meditation, some worship god by doing rituals with discipline, some do vedic sacrifices.
Consider the case of seeing him (not a material desire). Some people have to do a lot of meditation, but for some people he responds without doing much meditation. Does it depend on karma of when he has to respond?
Even the rakshasas do meditate to see Lord Siva, they will be with strict discipline in doing their meditation. But how will Lord Siva decide that it is the time to respond. He knows that the desire of Rakshasas will be evil. Why can't he just test more, the patience of them by taking a very long time? So that they get vexed and stop meditating?