In Kindergarten I remember learning to write the print alphabet in a non-alphabetical order. Later, in 2nd grade, we also learned script out of order.
The reason for this was that we were learning letters with common structures. For instance, I believe we first learned letters that had only straight parts: T, t, L, l. Then more complex shapes were added, with curves, such as B, b.
With cursive, it was the same thing, first learning letters with with basic loops, like 𝓵 & 𝓮.
Given that this was 25 years ago, I don't remember the exact order these were done it.
I know there was a purpose behind it, and I've found this Handwriting Teaching Order page, but it only loosely explains why the method works. Unfortunately, I can seem to find the right keywords to find scholarly articles on this subject.
In response to @Erica, some workbooks from more reputable companies base the their order on types of lines used. Free stuff I find is in alpha order. But the structured order isn't consistent, and I'm not sure how much difference it makes.
I'm interested in research-based information expert advice from educators or parents that have taught handwriting at home in a structured format regarding whether or not certain teaching orders are more effective than others, possibly regarding the acquisition of different fine motor skills or progressing through more complex letter construction.
I'm looking at this information as we're teaching our 3-year-old letter construction, and are trying to develop a long-term plan for progressing through the alphabet. Although we'll start with print, I would like information both print and script.