Gerolt gits gud.

[Bacent]

Exchanging the items one at a time still gives way more crystals overall due to the way the rng is working on trading in 10 or 50.
The difference is huge

Stating an opinion as a fact, lawl.

I've gotten between 100 and 250 when exchanging 50 at a time. Unless there's something that makes you 'more likely to get better loot for one at a time', then your basis has no foundation.

[Zova]

Its probably just taking a random number from 100 to 250 for 50.

I hadn't considered that, but it sounds like a good possibility based on some of the numbers people are reporting.