How to quickly eyeball maximum sum subarray?

Given an integer array, I want to find the continuous subarray (containing at least one number) which has the largest sum. There are some algorithmic solutions to this here: Maximum subarray problem - Wikipedia

However, I want to be able to eyeball a solution quickly (in about 5-10 seconds) given such an integer array of 10-15 elements (so not too many where it would be infeasible to eyeball in a short amount of time, but clearly greater than 2-3 elements), doing as little explicit pencil and paper calculation as possible.

Clearly humans are different from computers, so I was wondering if anyone had any insight/strategies/tricks as to how do so quickly by eyeballing in a situation with 10-15 elements?

To clarify, I am not looking to explicitly calculate the largest sum within 5-10 seconds, but rather I’m looking for the indices where the largest sum begins and ends.

Why do you want to do this?

Just run Kadane’s algorithm manually, it shouldn’t take you more than 10-15 steps, and all you need to remember is the sum and your current start index while you are doing it. As long as the numbers aren’t massive it should be very easy. I’m not sure you could do it any faster except when you have all positive numbers or some similarly degenerate problem.

I also would be fairly curious as to why you’d want to do this lol