From my own experience of farming/opening crates loot distribution in loot tables is not the same all the time. Once I had been farming locked crates for 1 hour with luck elixir + lepre (i.e. 40% of loot re-roll chance) and didn't get even a single crate. But sometimes crates drops very often. The same with opening chests/crates.

So, as for me it looks that loot share in loot table (sectors on diagrams in the first posts) is being changed over the time - sometimes it is bigger and you get more better loot than usual and vice versa