It depends on your goals. There are hybrids of the Oly lifts as well. A muscle clean is caught with straight legs, a power clean is caught in about a 1/4 to a 1/2 squat at most, and a squat clean, what is the only thing allowed in a traditional Oly Lifting competition is caught at the bottom position of a full front squat. You can catch a power snatch with minimal drop into an overhead squat, but for a full snatch, the only thing passable in competition, you need to drop into the full overhead squat.
Brian is correct. If you want to compete, you need to be able to perfrom the full versions of these lifts, and actually you can use more weight in the full version once you have the technique down, but if you are doing sport-specific training you can gain your explosion by doing hybrids of the O-Lifts, power cleans, power snatches, hang cleans, hang cnatches, muscle cleans , etc. But, as long as you can perform a full front squat and a full overhead squat correctly, I see no reason not to learn the full versions.
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