I don't think you need so much packs for nordgens. If you spend 1-2 packs per day for one nordgen, that would mean a lot for one player in season You don't need to power train some player a lot or to PT whole team. Choose instead few good players (which are in form, or which need specific strong skill, like gk defence or st attack) and spend packs on them
ST's are the best nordgens (if you buy one with good growth) Increase their att skill, when they get in form, they will grow like crazy because a lot of MOTM prizes (that also depends on formation, but that is another part of story...)

If you buy good nordgen, even without PT he can progress well...



Same player in the right bottom corner