For the context, please read https://gitea.wildfiregames.com/0ad/0ad/issues/8599.
I want to explain why I choose 5 gatherers for small ruins.
Many entities inherit from template_gaia_ruins.xml, with different amount of stone and metal. I will do a summary of them:
STONE
stone_statues_kushite_bird, stone_statues_kushite_lion, stone_statues_kushite_ram 200
standing_stone, stone_statues_egyptian, stone_statues_kushite, stone_statues_roman, stone_structure_small 300
stone_column_roman 400
column_doric, roman_rostrum, stone_statues_persian_lamassu, stone_structure_farmstead, stone_structure_house, stone_structure_tower 500
METAL
metal_statue_discobolus, metal_statue_poseidon 400
metal_statue_apollo, metal_statue_isis, metal_statue_wolf 800
As reference a small cut of rock has 1000 of stone and 12 gatherers, so I thought that would be a good deal to set 5 gatherers for something that has around 400
may even take it a step further, custCWA chart - Sheet10.pdfomize the weapons too (not the graphics though, just the stats, length, speed etc)
based on this chart, if you find it fairly accurate.