Is a 6.5" phone screen too small for Cubasis?

I was thinking of purchasing Cubasis to input ideas, mostly likely just to draw in MIDI notes/data. Having used the Cubase LE trial version I find this to be incredibly fiddly and annoying on such a small screen, I know I can play it live with the onscreen keyboard, but even to navigate to the beginning of an event to rerecord seems like it would be incredibly annoying and time consuming, and I image editing imperfect performances would be even worse. I don’t have or want a large tablet that is shown in tutorials and demonstration with external keyboard, is Cubasis basically useless on a mobile phone?