As others have said, avoid solo hiking above treeline in bad weather. And yes, a length of rope, like parachute cord, does work. With two people it's not as slow as you might think. On a few occasions, with seasoned companions, I've done some summits above treeline where the next cairn isn't quite visible yet one person goes ahead to find it and shouts back when it's found so that others advance. This works so long as it isn't too windy to hear each other other. It's a bit sketchy though, and requires close cooperation.
Wands aren't used much in the East, but are frequently used in other places. On each succeeding wand you mark the compass direction of the previous one, so that you can backtrack using the wands as necessary. I'd be reluctant to use them in the East as others are likely to come along and remove them, not knowing why they were there. Doing that in other areas of the country/world could get you in serious trouble.
Another safety system is to use a GPS to create a track of a route in good weather during summer conditions, and then re-load that track in winter 'just in case'. It would be foolhardy to use this method as a primary safety system, as batteries affected by the cold, rime ice on the device window, etc can make the GPS difficult to use. Having said that - I always carry a 'summer track' in my GPS during winter hikes, and while I've done probably hundreds of winter hikes, I've only found it useful once to use the summer track. Still, that one time kept us (probably) from thrashing around Eisenhower for an extra hour on a cold, miserable late afternoon day one winter.
Personally, I'm extremely cautious above treeline in bad weather when I'm solo. I can't really think of a good reason to do it, at least intentionally. I don't wish to sound judgemental re: Shincracker as I know exactly the problem he encountered around T-storm Jct. The trail coming up from the Great Gully and Gulfside are almost parallel for the last couple of hundred yards, and it would be easy to stray a bit left and head towards the ravine as you were headed to Madison.
As for cairns topped with quartz rocks - I don't think you can count on one route being topped with them and another not. Typically if there's a chuck of quartz around it's used to mark the top.
This is a good discussion, and it's good to air the various safety systems some of us use. Each person has their own comfort level, so what's over the top to one person will be acceptable to another. For new hikers reading these posts I'd suggest you go slowly, and try various techniques to determine what works for you and what is just too damn risky, knowing that with experience most of us push the limit further and further away. In the end, it's your neck - don't let someone talk you into risky behavior unless you know what you're gettin into.
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I double checked it and said to myself "this can't be West if this was West, then Cannon would be right in front of me." Right then the clouds parted for a brief second and yah, you guessed it, Cannon Cliff was right in front of me. The view quickly faded.
