Flight Bow Frustration

I got out in the glorious sunshine to test my 2 Boo/Yew flight bows head to head with the same arrows.
The first bow was slightly disappointing, but turns out that by applying all I've learned from the first bow and making minor changes for the second, I've made that one marginally more disappointing!

On the plus side, I didn't  break any arrows and the second bow, being a couple of inches longer can be cut down and reworked.

I had 6 arrows, 4 were pretty similar, about 280 grains with narrow footed tips, one was about 50 grains lighter and one a bit heavier (about 310 grains). The lighter one nearly always the shortest, and the heavier was also one of the shortest.
I shot all 6 from bow mk1, 6 from bow mk2. I then shot 4 from bow mk1 again to see if I'd settled to a better technique, but in fact the first ones were further.

Furthest arrow was a mere 268 yards.
Hey, ho, back to the drawing board, I may re-work the mk2 back to a 26" draw, as I have a set of 26" arrows.

Not much point in pics, I'll allow you to imaging the scene... an empty flat sunny field... some arrows sticking out in a desultory fashion... lone archer plodding disconsolately back and forth ;-)

A couple of the other guys did turn up as I was about to leave, so I had a bit of a natter.

I did have a bit of a mess around with the results by adding the distances achieved by each arrow to see if one performed significantly better, but with only 3 results for each arrow it doesn't mean much.
It did give the best arrows as the one which also had the single furthest distance. The shooting machine would help, but one doesn't want to perform too many tests and shoot out the bow. Mind, once the best bow is found, the second string bow could be used for arrow testing.
basic problem is too many variables.