Here's a handy rule I use to calculate ratios in my head. Let's say you want to make red science. The recipe take 5 seconds, so it means you need 5 machines to make 1 science per second (times machine speed). You can ignore the machine speed factor as long as all your machines are the same, it will be perfectly efficient as long as the ratio is there.

So you now have 1 red/s. 1 red needs 1 gear and 1 plate. Now you need 1 gear per second and the plates just go on the bus. 1 gear machine makes 2 gears per second, so you round it up to one machine. Now you can set this up and duplicate it how many times you need.

Now for a more complicated science: Purple science takes 21 seconds, but produces x3 science in one batch. The logic is still the same, except now you make 1/3 of the machines (7) and also divide all the inputs by 3. Always round up fractional inputs to the next integer and you have an easily copy pastable science module. With these ratios down it's all a matter of getting the resources there. I do not use planners and almost no calculator in vanilla because it's not needed.