Roaming without application fallout?

I have both Ubiquiti and Orbi systems at two separate sites.  I have tested WiFi calling (using FaceTime) and streaming video while roaming on both systems. I conducted roaming testing by walking inside and outside the house, forcing transition from one AP to another, and from 5G to 2.4G bands.  Other than an occasional blip when transitioning, both systems seemed to work fine. This was on an iPhone 5, which would also transition seamlessly to LTE once beyond WiFi range.  I didn't encounter any issues, so the testing was not extensive.  I imagine the results will depend upon the client deivce as well as the app used.