My stages are:

• Slow, inefficient and spaghetti factory but gets the job done, everything stuffed in a few boxes.
• get output parts split randomly along belts to make the more complicated products
• make a train, yay!
• run out of power, aww...
• bring out the spreadsheet, careful clocking and splitters to make "ideal" ratios of products to perfectly utilize maximum ore production
• Get a healthy supply of smart splitters, use overflow and stop caring about perfect ratios.
• retrieve products from "perfect" factories in spaghettified manner again to get the highest tier materials
• remake the base with better ratios and better aesthetics.
• sit back and realize you've spent 100 hours of your life on this, couldn't be happier.

Just about to relocate my base. Glad I haven’t built an extensive rail network yet

I mostly use belt speeds based on need myself, I find just going for top speed belts introduces potential issues with things not feeding correctly and overflows triggering prematurely... Besides, I find it more pleasing to see a line of slow build items moving to their destination than one at a time rocketing at ludicrous speed across the factory

Though, if we could literally rocket propel items from one area to another, that would be a different story ...