I use cross class skills from a variety of classes when making stuff for red scrips. My usual rotation depends on the amount of Progress I get with a Rapid Synthesis (if I need a second one or not) but it uses Steady Hand 2, Rapid Synthesis, Comfort Zone, Tricks of the Trade, Innovation, Hasty Touch, Byregot's Blessing, Careful Synthesis 2. That's a lot of cross class skills. If you are not taking all the crafting classes to 50 before working seriously on bringing them all relatively equally up to 60 you are making things harder on yourself.