There are however cases where Node neighbor = data[x+1][y]; does not require an index boundary check when you know that 'x + 1 < length(data)' for any 'x'

There are however cases where Node neighbor = data[x+1][y]; does not require an index boundary check when you know that 'x + 1 < length(data)' for any 'x'. This could be due to the iteration of 'data' excluding the last element or any other condition that's always hold.