In a nutshell? Tap as fast as possible. The game's tracking on where you press is incredibly off, allowing you to miss the colored tiles and get away scot free. In order to get a sufficient time, you need to rely on the RNG and tap as fast as possible, hoping it registers all the taps as correct hits. This can also be applied to other runs, but you are significantly less likely to be successful on runs other than 20, as there's at minimum twice as much room for error. I've found that using two fingers with one on the edge of the left center tile and the other on the edge of the right center tile is an efficient method, but I imagine there's better ways of going about it. (Specifically, from a grid point of view starting from top left, middle finger on the left edge of tile 2x2 and pointer finger on the right edge of tile 3x3). If anyone has any more efficient methods, feel free to let me know.