Some triathletes, especially those in shorter distances like Olympic or sprint distances, forego the use of socks altogether. This makes their transitions faster by removing that one often-clumsy thing they have to do in in T1 from their race.
But considering half Ironman races end with a 21.1 km run, I opt for socks because the risk of blisters is just too high.
In my first 70.3, I raced with 5-inch tall cycling socks. These were cool. These were what road cyclists wore. Normally they’re brightly colored or have some catchy saying or cool pattern on them, like “Do Epic Shit” or pieces of pepperoni pizza.
Mine had no amazing pattern, but still, they were tall. And they took me like 3 minutes to put on.
I had to uncrumple them right-side-up, push my feet in, pull them up bit-by-bit, straighten them, negotiate the left one under the neoprene and Velcro race chip, etc.
That was slow, but I thought that was normal. More than 10 half Ironmans later and I’ve only ever used the 1-inch ankle socks which are far faster and easier to put on. Plus you don’t look like a roadie.
So there you go. If you have to wear socks, choose short ones that are easy to put on.