I don't get to see very many Spey casters here where I fish but I have noticed something worth mentioning.
I came from almost 20 solid years of single hand Spey casting; mostly snap T and snake roll style casts with a Perry poke here and there where needed. I am a self taught 2 hand caster who may not be perfect but one thing I've been keen on since my first 2 hand cast is............................... Never allow the fly to be anchoring anywhere to my rear, period
. For my applications here the whole point of going to 13 & 15 foot rods was to completely eliminate the need for any back cast space
Call it a genetic trait for self preservation or call it unconventional casting style, I very seldom have the fly in any position that when executing a cast it can rise up and either strike me or my rod tip. I have seen some people spey cast who use or need about 25 or more feet of clear space behind them when casting. These folks have the fly traveling right past their shoulder and heads when casting.
If I had your experience and were reading this, where a guy claims to be doing Spey casting without ever hooking himself or hitting his rods, I might try to find the secret to his style. Trying to simplify this I will say; start with medium range casting (40 - 60') and work on keeping the sweep and anchor to your front never setting the anchor behind you. Another thing that will help is to practice casting either strait across or to quarter up stream from your position not quartering down. This will eliminate the amount of free space behind you unless you are standing in the center of a river.
Do your practice fishing with your back close to shore and know that sending an anchor & D loop to your rear will result in snagging trees or brush. This in combination with directing casts across or quartered up will force you to place the anchor to your front left or right depending on which side of the river you are fishing from. The obstacles to your rear are like hobbles or a governor on your style and will dictate a safer cast.
Rather than focusing on distance as many of us are prone to do, keep the sights set on smooth safe casting. With patient practice while fishing you will learn where to have that fly every time so that you will not strike anything when you cast. Perhaps I was more concerned with fly placement because my small stuff are tied to Bartleet #4 & 6, and the salmon flies on Gamakatsu 2/0 standard salmon all with barbs. I was acutely aware of what the result of hitting myself would be on my very first cast.
If you are using weight, any kind of weight, lose that and fish a floating line and unweighted fly until you have it down. Then begin to experiment with adding some resistance in the way of tips etc. as you move forward.
For those who may not agree with how I explain this I'll paraphrase the late Hunter S. Thompson here, 'Although I can't recommend this for everyone, it's always worked for me'. He however was not discussing the Spey cast