Im sorry but if youve shot a bare shaft any kind of distance in any kind of wind, you'd see without feathers the direction would radically change. There is nothing "steering".
I shot one recently in the wind at 20 yards. It ended up 80 yards out in the field and never touched the target when it was dead on half way.
I cant answer your question for you. Only you can.
But... Please allow me to add food for thought.
For me two or three things come to mind.
1. What is it exactly youd GAIN by cutting back on fletching? (BTW 4, 4 inch isnt cutting back, its roughly the same amount of surface area as 3, five inch.)
2.Feather clearance? Some kind of feather contact is WHY we shoot feathers. Want less for some reason? Put on an elevated rest of your choice. Or maybe just take a better look at your set up, no offense meant. It's just that 5 inch seems to have worked super for a long long time.
3.More speed? How much? 1-2? fps maybe? Is that really going to make an iota of difference? And do you stop there or go to straight fletch, release, etc? 10000 people online will tell you that those give you more speed as well.
Then....what are you RISKING?
A longer time might be needed to stablize your arrow for good penetration?
Slower recovery on a poor release, slight arrow contact with a leaf etc?
I'm not saying a tight helical four inch feather wont work but is just enough...."enough"?
I'm old and stuck in my ways but...it "aint broke" so I "aint fixing it".
If I am to err, I choose the side of stability. In the "heat of the shot" I rather doubt I do it all "correctly" and if extra stability counters for a poor release....I have enough respect for the animal to use it...always.
The draw of traditional archery and hunting FOR ME, is to "use what has worked for decades and decades", regardless of the speed, regardless of the distance I must be at to shoot something humanely, etc, etc.
Simply put......the old ways. How old is up to each and every one of us and I will defend your right to do so.
I for one, have no "need" to question a lot of the ways our trad forefathers did things....I only wish I could do them half as well.
Some like to "tinker" with everything. Nothing wrong with that, but the four inch thing??? I am willing to bet the ranch that 50 years ago someone else thought the same thing, yet the five inch feathers OR BIGGER are the norm after countless animals taken.
I'd like to think that decades of others hunting with trad equipment has filtered the best of most ideas to us.
Helical fletching, two blade head penetration superiority, and (no offense to those that dont agree) heavier arrows are examples of a few.
and PLEASE....I mean NO OFFENSE, even if I am poorly adept at wording things correctly.
Less fletching "works" but what are you gaining, and at what risk?
Too many I see in threads are always talking "when shooting 3D". 3D equipment is not at a living breathing creation of God.
Please dont confuse your "findings" shooting 3D with hunting situations. Almost nothing is the same except both are shot with trad equipment.
Only you can answer a question when doing so. What risk am I taking and is it worth it?
If you feel there is nothing lost and you have somehow gained something, go for it.
Some here will offer other opinions and I'm glad they will.
FOR ME.....I'll take the old "tried and true" and love using it.
Ill not get into a debate but do appreciate the opportunity to offer my 2 cents.
God Bless