Another issue with increasing to a phone’s maximum volume over a fixed timeframe: a phone with a very high maximum volume (like my Galaxy S8) gets to a volume sufficient to disturb others very quickly - in my case, with the volume increase duration set to 24 minutes, I usually shut it off within 1 minute, and never get to the 3 minute mark. The steps in volume are so significant I can hear them happening.
Most phones’ maximum volume is designed so you can hear media in a noisy room and ringtones over busy traffic. The alarm isn’t “gentle” if it gets too loud for the user very quickly. There’s no way to use this app to listen to music for any appreciable length of time while waking up.
Edit:
On further investigation, this old report/request also matches: Lower minimum volume level
Is the app still supposed to use its own media player and volume settings? If so, why is it falling back to system-wide settings (evident by the huge increment consistent with the available levels in system sound settings) on so many phones? Should this be classified as a bug instead of a feature request?