I've always been fortunate to get the peep pointing about perfect at brace and go about perfectly straight back during the draw. I don't think I've had to let down and not shoot from my peep being twisted one time in the last 10 years. If I get my peep right like this, then the d loop doesn't have to do much. I might use the d loop to correct a very small deviation in the peep (never more than 10 degrees and usually 5 degrees or less).
I'm going to go with a Bowmar peep tuner next string change. But the only secrets I have are using a good aftermarket string, knowing that even that string will take some shots to settle, twisting the top or bottom of the string (I still don't get why the end matters but it does), and not serving above and below my peep like most folks seem to like to do. I use a similar technique similar to this but with more overhand knots on the legs formed by the string splitting.
I use the clove hitch variant. With multiple overhands, this holds the peep better than the standard method. Several companies/well known folks use some variation on this (Gillingham, Bowmar, Hamskea, Bee). Also, if the traditional serving method compresses the triangle above and below the peep, then this can cause twist as the load on the string changes during the draw and thus the forces acting on that triangle area. The linked method is unaffected by that.
One tip is before tying in the peep, I'll wrap it and the string in several wraps of masking tape and shoot to let things start to settle. The tape is there to keep the peep from shooting out of the string. If I shoot enough, then I won't have to tie in the peep and then have the string settle after 50 shots and then have to re-do my work and untie the thing. 6 or so good wraps of white masking tape and it isn't coming loose at the shot.
Here's the peep tuner. Some folks think this is cheating, but it works and is easier than twisting strings.
FIX PEEP ROTATION Keeps your peep perfectly square Easy install and adjustability Works on any bow string
bowmararchery.com