Waiting until heat is completed to exit pool?

I was swimming at a meet today, and I noticed that most/many swimmers get out of the pool (or at least in my heats when I was noticing it) more or less right after they're done with their race. Back when I was about 9 (1993ish), I remember my coach told us before the local summer swim league championship meet (it was my first) at UNC's Koury Natatorium using electronic timing, etc., that it was good sportsmanship to wait until the entire heat is finished with their swim, and then get out of the pool. The reasoning was never explained to me at the time, but I can infer a good reason: no one has to finish the race alone (there are probably other good reasons). I've generally adopted this practice for the most part when I swim in meets, even though this can impact the operation of the meet (namely, if it takes longer to exit the pool, the meet takes longer, unless you use dive-overs). And this practice can be problematic if you win the heat, and it takes a long period of time for the heat to finish (say 5 minutes). I should also note that I haven't paid a great amount of attention to this, and that the heats that I generally swim in are early heats, which tend to have larger time spreads (which would skew my perception). Furthermore many people who didn't have the lengthy experience with competitive swimming that someone like I would might not know about this idea. And in the grand scheme of things, waiting doesn't make you a better person or a worse person than anyone else--it's just a custom. So what does everyone think about this kind of thing? Is it something that matters or is it largely irrelevant? And is the practice of waiting commonplace or haphazard? Patrick King