Nick, you are reading whether an analog pin has bled down through a banana to a certain threshold voltage. And that is taking 16 bit values and 105 usec reads plus code you don't need.
A pin used as digital INPUT_PULLUP will do all that and simply present you with 1 bit per banana. You can read up to 6 bananas at once with an UNO for IIRC 16 bananas (maybe 18?). You can read whole sets of 8 with a MEGA. When you read the pins in a Port, all the bits are right there together in the same byte, the evaluation and organization all part of the wiring and code allowing you to use LESS of both to do the job.