I've always noticed that the ones to grow the fastest and the biggest are always more outgoing and friendly, not shy at all of human presence. On the flip side, the ones that are shy and stay hidden in the moss most of the day and are very skittish of my presence grow much slower and are smaller.
Or perhaps the bigger ones are bigger because they were less shy/more outgoing and therefore ate more, and the small ones are small because they were shy in the first place and therefore didn't eat as much…Chicken or egg…hmm?
I must have an outlier if this is the case. My smallest one is the most outgoing and the other 3 hide most of the day. Hopefully this doesn't point to a health issue.