I'll be looking forward to your observations now that you are specifically looking for it. I think that you are right, different chicks go through this differently. Some possible causes for differences might be time of year or diet. I think heredity might play a big part, some chickens are slow molters and some are fast. That's not about how fast the feathers grow back but how fast they fall out.
I've never really observed it to try to figure it out. I typically have three or four different age groups together and can't always tell who is molting, it's just that some feathers show up. Usually it is such a gradual process most don't look like they are molting.
@Xerocles I've noticed some differences from one molt to another. Usually it is not that dramatic but occasionally it is. I can sometimes see patterns in juvenile plumage that do not show up in the adult plumage. One example is the mottling gene. It's a recessive gene so unless you have both genes at that gene pair the mottling gene it will not show up in adult plumage. But I often see it in juvenile plumage when only one gene is present. Here is an example. Those white "mottling" pots do not show on the adults.
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This is my most striking example. In her first adult plumage this mixed breed hen was a normal black mottled chicken. After her first adult molt at about 1-1/2 years old she came out like this. I think this is called the exchequer pattern.
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