Basically yes… You can expect to get AN AVERAGE of 15-20 units per uncollected arena crystal (the ones for 10k chips)… The more you open, the closer you will get to that average…Also, the units from each milestone add up over time.
long term which arena crystal you use doesn’t matter-the smaller crystals will get closer to ‘average’ payouts sooner because you’re opening more, with smaller amounts of rewards; the larger crystals give you fewer chances to get units, but give you more units when you do, so it averages out in the long term - the real benefit is the small chance of a higher tier Punisher.
Definitely recommend opening the smaller crystals. I am always frustrated when I open 500k and only get gold... so I stopped doing that and went for the safe option.