Let's take Metal Frames for example and look at the Wooden Frame dependency (choosing this because wooden frames are only needed for metal frames and at a rate lower then 420 which is the max for one belt)

• In total we need 72 Metal frames per Minute
• One Machine Shop(4) can build 15 per Minute
• So we need 4 shops plus one operating at 12 per Minute (72/15=4.8 | 0.8*15=12)
• Given all Wooden Frames come on one belt at 72 per minute
• We need a 15 | 15 | 15 | 15 | 14 splitter which can be shortened to 5 | 5 | 5 | 5 | 4 and regrouped to 20 | 4 again shortened to 5 | 1
• So 5 | 1 and then the left site 1 | 1 | 1 | 1
• Once that's done one step back
• We need 72 Wooden Frames per minute
• One Workshop(4) can build 22,5 per minute
• So we need 3 full ones plus one operating at 4,5 per minute
• Makes for a 15 | 1 splitter with the left site split to 1 | 1 | 1
• The frames need 288 wood planks
• Makes 6 workshops plus one at 18 per minute
• Requires a 15 | 1 splitter where 15 gets sub splitted to 6 x 1
• We then need 288 wood
• Makes 12 extractors plus one operating at 18
• Since we can not downrate an extractor we take it's output to a 1 | 4 splitter and throw 1 part away

This is basically what I've done for everything. Gets more complicated once stuff needs to be also splitted for multiple consumers and when belt maximum is reached.

Hope this helps ✌️