You're understanding the maths (and what ME and PE actually ARE) incorrectly.

Your corn silo example is backwards, because it is applying wastage of one process (farming the field ... or, I guess refining would be the closest here) to the material requirements of another process (filling a silo .. or building a ship). I think the reason you're pointing this out is because the base materials are hidden from "general usage" and the BPOs just show the answers of the actual math that goes into figuring out the numbers.

1. EVERY character in this game has a 25% base wastage factor. Every level of Production Efficiency you train reduces this inherent waste factor by 5%. That is, PE 1 is reducing your character-induced waste to 20%, it is not necessarily a real-world gain of 5% (due to how the formula works, and the sheer volume of material we're talking about). Think of it like ... I dunno ... how good you are at carpentry.


2. You're also thinking backwards on how the waste factor goes. There's a rule of thumb with carpentry (or well, most any "manufacturing" profession) that you take your "needed materials" and add 5% (or so, I use 5%).

Using a 200' long fence, the BPO will have the following "base materials".

20 4x4 posts (they'll be spaced 5' apart)
200' 2x4 stringers (2 stringers between each post)
however many pickets (I don't care here).
5% Material Waste

Now, if you only buy the base materials, you will end up finding that somewhere along the line, there's something wrong with a post or a stringer, so you add in the BPO 5% waste factor when you buy your materials from the lumber yard, and end up taking home 21 posts and 210 feet of stringer.


And then, using this with your skills, you might end up needing more material. Let's say you have L4 PE.

The "Wooden Fence BPO" will then show the following:
Materials needed:
Fence Posts : 22 (you) 21 (perfect)
Stringers : 220' (you) 210 (perfect)

Now, if the "Wooden Fence BPO" had 10% material waste (you still have PE4):
Materials needed:
Fence Posts : 23 (you) 22 (perfect)
Stringers : 230' (you) 220' (perfect)



edit --> ME waste also applies to "Extra Materials" that are also included in the Materials list -- so a Shuttle that has 2500 base + 500 extra will have ME and PE waste factors shown against 3,000 units in the "Materials" columns, rather than showing whatever the ME/PE waste is for the 2500 materials and 500 Extra Materials. This is just a display bug, and you can work it out backwards to prove this (or use something like the fuzzwork BPO calculator that has the display operating properly).

edit 2 -> clarity