press button function really easy on pc but. It will be challenge for you If you try on mobile you cant even fill faster before zombie cums. after you lose one heart maybe you stop sex scene
The button is too small to drum on it with two fingers, I guess?
Depending how touch friendly the game is supposed to be, the mini-game could be different. There are minis that are ridiculusly easy on touch, but hard with mouse.
And there is of course the itsy bitsy mobile phone displays. You can't see the screen with your hand in the way, tapping stuff. An outrage for a porn game ;-)
You could cheat and connect a mouse to your Android phone. But I think it will not give more click events to the app. If you mush with many fingers, it tries to read a gesture or interprets it as a single tap. I tried with some app and that one registers only two clicks, when I alternate between tap and mouse click.
optimal is always subject to the thing you want to achieve.
a simple mechanic is timing. have a metronom or circle and when the indicator is good, tap/click - does not matter. i think seed of the dead implements something like that. it is also about zombies and struggling ;-) you fill up a bar by clicking and if you click at right time it goes up, wrong time it goes maybe even down. but i think there was additional mechanic, like measuring how fast you filled the bar to give you better result or something like that.
point is, you need not make quickness of input device and hand be the mechanic. But it also can be rewarding. I know that from fighting games, quickly tapping to escape a hold and so on. But that was more like 2 seconds of mushing the controler buttons. it is a form of stress release.