In Supertraining, Siff suggests that no more than 40 repetitions be performed in a session and that one or two sessions per week are appropriate. Of course, these recommendations apply to athletes with the correct preparedness. These guidelines were for use during training designed to raise special strength (aka increase vertical) and were also recommended to be supplemented by a low volume of other strength exercises.
He also suggests that up to 20 repetitions might be performed at the end of a technical session (aka sports practice) and they might be performed up to 3 times per week. Again this applying to more advanced athletes with the proper preperation.
So my own advice would be to work up to it. Spend 4-6 weeks doing submaximal plyometrics such as box jumps, low depth drops (without the jump), skipping and bounding in a low-to-moderate volume before your training sessions and perhaps include 20 repetitions of sub-max depth jumps (8-12" box) in one training session. After this acclimation phase, then you can get into more of a traditional “shock block.”
Of course, this is assuming you can squat more than 225.