Most people I know learned using the snap shooting method, as I did. I was introduced to the 2 sec hold when I went to Rick Welch's class. Rick believes a 2 sec hold is beneficial in order to stabilize yourself. The system he teaches is not gap, so there is no actual work or thinking to do during the 2 sec hold. In fact, any work or cognitive thinking during the 2 sec hold would be destructive to the shot. As a result, 2 sec seems like 2 min at first. It takes effort to learn to hold for 2 sec doing essentially....nothing. Obviously, the only reason for doing it is because it makes you more accurate. If it doesn't make you more accurate, then don't do it!
(I'm reminded of something either Mark Twain or Will Rogers said about investing: "What you want to do is to buy a stock when it's low and sell it when it's high. If it doesn't go up, then don't buy it.")
I find it difficult to snap shoot when I am used to holding. Evidently, Rick Welch does too. I asked him one time how he deals with the speed shooting events at trad tournaments. He said he just holds and shoots and hopes to make up the points somewhere down the line. Of course, in the trad world championship, there is no speed shooting event.