What I think would be a useful reference, probably as a showcase post rather than in the official docs, is in addition to examples, a collection of resources that relate to system structure/design and how things will impact performance / downstream analysis / maintenance. For those of us (me!) that don't have a compsci/database background, we may make design decisions in the creation of entity lists and the forms that use them that are sub optimal and result in additional work required or poorly performing forms.
Are there textbooks / courses / videos that would help guide data hierarchy / structure / relationships to result in efficient and more readily manageable entity lists & forms that people can point to?
Along these same lines, I will just say that the most common thing I’ve struggled with is ideal group structure. No matter how many times I change question orders, it always seems like there is a more ideal way to put certain questions which sometimes involves changing what group they are in. With several nested groups and/or repeats, it can get messy and I haven’t really figured out a good way to figure this out on the front end.
I think there's an abundance of well designed forms in use which solve a combination of problems. If we had a repository of these forms, or maybe just form fragments solving exactly one problem with correct and consistent annotations, they may form a good knowledge base for a chatbot like the brand new kapa.ai.
I find form building challenging because I have to abstract what I want to achieve into a language with lots of specific terminology, then find similarities to other case studies explaining how they implemented their needs. Maybe this mental translation of concepts is something kapa.ai could/will help to bridge.
Last, as for ideal form design and flow, it's always been an intense two-way street between the analytical needs of what we need to capture versus how we practically can capture within the flow of field work. An invaluable resource there was having a quick feedback loop of form design, test data capture, and analysis (in my case, using the ruODK Rmarkdown template, but anything to quickly parse/map/summarise submissions would work just as well).