Even single hard nodes will still sometimes end up giving you 0/8 or 0/16 for a day. Statistically speaking it's probable to get 2-3 shards per day on 8 sims, so about 5 shards every 2 days.
Statistically speaking, Logray shares a node with 5 other characters, so has a 1/6 chance to appear each time. With 8 shifts in 2 days, it's highly probable to get 5 shards every 2 days. Over a period of time, it should be faster to farm Logray in the guild store than a single hard node.
That being said, probability does not guarantee success. Even over 2 weeks, it's possible to get 0/56 Logray appearances. It's also possible (but less likely) to get 56/56.
What would be most helpful would be to organize a group of players to track the character appearances on that node over a period of time. That way you could start to get a picture of whether the characters there have a statistically significant frequency more than any of the others, or if it's an even distribution.