I agree, the speed needs to be known or estimated. But instead of 5 yards, I would shoot 12 to 40 yards to calculate the drop. Anything under 10 yards will most likely give you some confusing results. Under 10 yards can cause you sight marking to be way off and depending on your peep height, it can be quite a bit. The lower the peep, the shorter the distance one can shoot at without it reversing and the higher to peep, the longer the distance one needs to shoot at to avoid the reversing.
At some 3D shoots I have been to in the distant past, there would be a target set up at 3 yards. To correctly hit it, you had to aim as if it was 75-80 yards.
As for 1 pin, I have hunted with 1 pin for many years. I am deadly from 10 to 40 yards. The sight picture is clean and uncluttered making for better low-light hunting. With modern fast bows, multiple pins can be closely stacked together, and this can block a lot of the sight picture. This can be difficult in low light to see the deer thru all the pins.
For a hunting range of 40 yards or less,
280 or more fps, 1 pin works well.
250 to 280 fps, 2 pins works well.
250 or less fps, 3 pins works well.
If your hunting range is 50-60 yards, you will need to add an extra pin or two to cover the increased range.