I think that is very interesting and almost certainly exactly what happened. If they ordered barrels in lots it makes sense to make them up in advance and number them so a few did not walk away. They probably roughly struck them to make sure there were no hidden defects. Then assigned serial numbers based on matched weight and contour.
The mixing of old stock with new stock also explains why you see features on guns made later than the feature had fallen out of normal use. It could just have been in the normal production sequence but used a later numbered barrel stock first then a low number later. That would explain why you can see guns with different features in a out of order serial number sequence. It might not be that they were going back and forth in features so much as that their production instead they used old low barrel serial numbers on later new gun which means they also had used higher serial number on old style guns with.
Has anyone ever tried to figure out how many guns they could have produced a week? If the number is 50, 100, 150 then you could figure a fairly accurate yearly production. Did it fluctuate much over the years? Then based on pattern dates see when features were added to guns. I know they often used a new feature before they had it patented. Sometimes they seemed to decide it was not improvement and dropped it and moved onto another. One thing I always liked about LeFevers is that they ask as many questions as they answer.
