>>717931125
Pay attention to these numbers on the right and work backwards.

Take a look at how fast your things are being made and work out how much materials you are making in that time, because in basic assemblers a belt is made 2 per second and grabbers are made 1 a second, but green science is made in 12.5 seconds.

So you will need a ratio like this:
>Belt : Grabber : Green science
>1 : 2 : 24
That means;
1 belt assembler is making 2 belts a second and is enough for 24 every 12s
2 grabber assembler are making 2 grabbers a second and is enough for 24 every 12s
24 green science assemblers are making 24 green science every 12 seconds and need 1 of each ingredient to start again.

See how they match up?
The only unfortunate part of this is that grabbers and assemblers tend to be greedy and eat more than they need to have backup for their next recipe.

So in my pic i have way too many belts being made, I could go with 1 less assembler, but it's not that big a deal really, I could just mess around with modules to adjust speed, but again; not that big of a deal to have a saturated belt full of stuff waiting to be used.

It's just to keep in mind so you're not making like 12 belt assemblers to satisfy 12 green science assemblers is all.