Sizing factories for a train base

Hello, First time player here, but I come from Factorio so I love trains and I am trying to build a train base, i.e. multiple small scattered factories and move stuff around with trains.

Now, for project Assembly, sizing the factories is clear. Decide on a target (e.g. 100 versatile framework per minute and size intermediate steps, if any, accordingly). But how do you size suppliers to your depots? You just size them with dimensional depot upload speed? You just overproduce a bit and whatever gets there gets there?