not really i dont believe in luck
I believe there is a balance for esis. In past i felt this on my own by camping mobs that had lower esi drop rate. When i started looting i had like 6-7 esi in few hours. Later on i started doing SK waves and got 1250 1250 and 1000. After that for 2 years i didnt loot any 100+ esi's.
I have some friends who only hunts big stuff and never had full esi, my only explanation is they get small ones.
Another observation is the quantity of esi's. If lets say (all numbers are just an example) in a period you need to shoot 60k to generate 10 ped esi in another period is 90k. Thats how i feel it is "dynamic". MA only playing with the quantity we spend increasing and reducing from time to time, this makes the fluctuation of the price.