I have used the contrast method for vertical jump training with great success; typically employing active recoveries lasting 5-8 minutes between the first and second exercises.
Right, regarding speed training, I personally think it an entirely unnecessary risk to employ such a choice of means (overspeed following an intensive means) as the overspeed is already a very slippery slope.
Resisted sprint followed by unresisted is as far as I’ve gone and both actions have always been 30m or less.
A very questionable program in my view as the instruction of weight training mechanics is clearly haphazard and this combined with such risky speed development tactics makes for an undesirable gamble.
But like most programs that share similar combinations of questionable coaching/programming tactics and sporting success the trend is always continuation as the powers that be rarely possess the awareness to see the training problem and, as a result, the search for improvement typically looks right past what seems obvious from an alternative point of view.