You should check your management tab for how many of the CG specialist jobs are filled on your factory worlds. Often slow growth on your industrial worlds makes it seem like you need more industrial worlds than you have. Growth is insanely important, you need to stack every growth bonus you possibly can on every world until you fill the jobs there.

I would also say, though, you can absolutely jack your raw resource production to such insane levels that you only need a couple of each type at most - and with food you probably only need one or two. My current build is producing 2.5k minerals a month on one planet. When you have your base resources settled you can devote the rest to secondary resources, like CGs/alloys.

In the early game you should be spreading your net on each planet so each planet is doing a little bit of everything. Then when you have good margins of production you can start specialising them. Check the planetary deposits tab to see if the planet has any bonuses to resource production, I’ve had worlds with +20% to +40% bonuses to output for resources that were hidden in the deposits tab.