The exact experience will vary between assistive technologies, in some cases they may change the intonation of what VoiceOver reads, or add additional options for navigation, sometimes they will disable that assistive technology from accessing the element, or change how the assistive tech functions. The key is knowing when to customise; as with most accessibility considerations, custom controls are a must, but also headings, elements that change their state, controls that play sound or other media, tabs, path-based interactions, and others need their traits customising to ensure your app is accessible and usable by assistive technology.