If I remember correctly, the improved GP regen traits are locked behind first completing the level 70 class quest then reaching level 80. If you haven't completed the class quests, that will help. Between that and Hi-Cordials, I usually don't feel like I'm stuck waiting that long for GP to regen. My GP keeps up with running between legendary nodes, even if I'm logging in and out between 2 characters for each node.

I don't bother farming for scrip unless I'm running low on Hi-Cordials. If I'm out gathering, I'm either gathering materials I need for crafting or working on achievements in Diadem. If you're gathering legendary materials on a regular basis, Extraction will take care of most, if not all, of your materia needs (especially if you're using a Squadron Spiritbond Manual and Superior Spiritbond Potions). It's easier to farm Aethersands than farm scrip to buy them. There are the vanity items purchased with yellow scrip (housing items, chocobo barding, orchestrion rolls, etc.) if you want them.