Insulating a metal shop?

I Have a 60x40 shop and my quote to spray foam was over $20k. no way that was gonna happen.
I have started doing rockwool batts, I like that I can do it in sections, and on my time, and not have to clean the whole shop out. It's frame with 2x8 lumber so I can use R30 rated batts, and then just put plywood/OSB panels over it and be done. Rockwool is great for a shop enviroment , doesn't absorb moisture and is fire retardant. In my research before starting it seemed to be the best option.