TL;DR
Concrete recycling should take 1/10th of time it currently takesWhat?
Some of Factorio items, such as: Concretre, Refined Concrete, Biter eggs, Nuclear fuel cells are produced in bunches of 10. (and copper wire/iron sticks 2 per craft)Recycling time of those items should be calculated as 1/10 of the recipe to be proportional and consistent with idea of "recycling takes 1/8 time of the production" So if 10 blocks of concrete takes 10 second to produce, those 10 blocks of concrete should take 1.25 second to recycle.
Right not it take 12.5 seconds to recycle 10 blocks of concrete - LONGER than time to craft them!
Why?
Consistency and predictability of behavior. It also notable that some mods made some crafting recipe to produce a lot of items, for example Ultracube have some recipes that crafts in bunches of 500 and now it would make x62.5 times more to recycle that crafting process than to made one.IF any material should be "hard to recycle" there should be obvious and deliberate multiplier that will tell to player that "This is hard to recycle, it takes 900% more times to do so"




