Picking yugioh packs?

i heard when picking yugioh packs you should get the lightest pack because that will most likely be a holo card in the pack. does this apply for the new packs 5D's or the packs from gx ex: cyber dark impact,enemy of justice: i picked out a cross road pack and got a hanuwata super rare and i bought another pack it weighed more and got a rare and for the gx pack i got 1 heavey pack and i got a holo and i then a light pack and i got a rare?