I've been using 4x5" feathers in a 90° plus pattern (+) for quite a while now. Shoots great and is very forgiving if I have to "make" a shot in an awkward place or position. I bare shaft first, then paper tune so I know the flight is very clean off the bow anyway.....
I don't target shoot, other than stumping etc, so I'm really not qualified to comment on extra drag and/or drop there may or may not be. I really only hunt, and often up close in some really thick nasty cover.
I use the nearside feather touching the tip of my nose to "trigger" the release, hence the "plus" pattern. Don't even think about it touching my nose now, as it has become an automatic subconscious thing. Works great for me. But if I'm using a mates bow and his arrows, the feather isn't there for me and I struggle a bit.
4 fletch is "a" way of doing things, and it's "a" way that works very well, for me. But it's "a" way, not necessarily "the" way.
So is 4 better than 3 ?? The jury is still out on that, but have a go with 4 fletch for yourself, experiment some, you might be surprised. As you can see from the other posts, many people use it, and like it too.......
Best
Lex