Crystal use for shards

1 refresh is worth it. Beyond that you're rolling the dice.

its really dealers choice. buying shards for crystals is pricey, but its guaranteed. refresh on a HN could yield 0. over the whole time of harvest the average will work out ok, but i'm still not sold on refreshing HNs.

Premium characters cost 320 crystals for 4 shards. For 100 crystals (50 for energy refresh and 50 for node refresh) you get 10 rolls. For 300 crystals you get 30 rolls. You have to have really bad RNG to constantly get 4 or less shards on 30 rolls. Plus you can get some gear (getting stun guns from Holdo's node is fantastic).

One refresh is worth more than buying from shipments.

I'd go for the refresh myself at least on the hard nodes with nuisance gear parts on them. Like the mentioned Holdo node, I'm not interested in Holdo myself so I won't be farming her but if I were and I ended up just getting stun guns instead I'd be a happy man.

I'm farming Holdo and getting stun guns at the same time is fantastic, especially because she needs so many.

Refreshing a node costs 50 crystals with an expected payout of 1.66 shards, that's 30 crystals per shard (60 if you include the cost of the energy refresh). Buying from the shop costs 80 per shard. Over a full 330 shard grind, you would spend 6,600 more crystals to buy from the store than to farm. The farm will also include gear, but the store will be faster.