Olympic distance athletes usually use Sprints as "B" races to "get their feet wet" again and to reinstate racing habits, etc. Not a bad thing at all and great way to enjoy the love of the sport and the pacing of a power race. Using a Sprint race as a training tool for the Olympic distance and as part of a periodized schedule (see articles on phase training) is a very different tact than these approaches.
When training Olympic distance athletes I make the following recommendations on how to integrate sprints as part of their BUILD and RACE phase of training, usually two sprints as part of their "A" Olympic race preparation. So why integrate two races, incur additional cost and driving training closer to the injury curve than normal RACE period training requires? Well, aside from the aforementioned "practice racing skills", blah, blah, blah, the structure and emotional content of a race can prepare you for a your "A" race like few things but if only done correctly.
Select sprint races that are close to the end of the BASE and BUILD phases just prior to RECOVERY weeks. At the end of the BASE phase you are looking to determine if you can hit your time goals comfortabley meaning it is a controlled pace not a sprint pace. Sorry but you're not racing - you're there to determine at the end of your BASE phase if you have built a strong endurance base. A perfect set of goals would be your planned Olympic pace for each event - you may not be leading the waves but then that's not the plan.
The sprint at the end of your BUILD should be about whether your training has affected your limiters as well as whether your time goals are viable. Yes, BUILD is not that stage where you're working speed/power but endurance accounts for much of your speed and power improvement: if the needle ain't moving then you may not be able to move out of BUILD.
Picking the right sprint races is the difference between getting in some races before your "A" Olympic and using the sprint distance to improve your Olympic. Choose a sprint profile that matches your Olympic race or as close as possible. This can be hard especially here in New England where most early sprints are pool swims with one of the few exceptions being the Max Performance Season opener.
Post race review becomes a real thing. You placed blah blah out of blah blah in your age group - a big who cares. Was you swim time in line with what your Olympic goal is? Was your positioning correct? Did you have the discipline to sustain the speed and power profile planned? Was the run a death march or did you finish knowing that you sustained a disciplined pace?
What were the mental and emotional cues during the race? Was the effort one of survival or execution? Does the swim continue to be a life and death effort, was maintaining cycle effort a balance between aggressiveness and safety and comportment? During the run did you decide to mail it in? What were the mental and emotional high and low points of the race? You need to know these and the whys because they will assuredly come up again at your Olympic. Case in point, most sprint athletes moving onto Olympic condition themselves to survive the run instead of attack it - and it has nothing to do with conditioning. As Yogi said 90% of the game is half mental. Possibly of all the things you'd discuss with your coach this may be the most key and it could lead to fundamental changes in how you train.
Approaching the sprint distance as a tool for your Olympic can add some excitement and discipline to your season planning. Sprints are approaching the cost of Olympics and just doing them for fun is quickly becoming an expensive habit. This approach can provide some discipline and also add some excitement as you see how your training is working...in actuality not a training session.