Very often sub microflows are part of a set of microflows working together. For that reason it's sometimes tricky to reuse them. I really think it's not only tricky but a real risk for bugs.
Say for example that you pass a list into three microflows and at the end you commit the list. The sequence for this sub microflows could be important and if you call a sub microflow from another place, would you also commit the list at the end?
For me it would be helpful if you could see microflows in the same folder as a traditional class structure. How the class works is ‘hidden’, you can only use the class by its public functions. So say that you can mark a folder as a “class structure” and microflows in it as either public or private. A private microflow can only be called from another microflow in the same folder. It should be very helpful to prevent your model for making easy mistakes.
E.g. you can have the following structure (just a silly example):
ordercalculation (folder)
- PUB_Order_Calculate (public)
- SUB_Order_GetLinesTotal (private)
- SUB_Order_CopyVATToAllLines (private)