Correct, however, trust me in that the interplay between the varied training elements on all days yields positive results; even though the sprint volume on the second speed day is considerably lower than the first.
My suggestion is not theoretical, I’ve done this for a few years now (only at certain times of course) and the results are continuously positive.
Additionally, I should have first clarified that the workload adjustments need not apply to all training modalities for a given day. Meaning, if the sprint volume is reduced to 50-60% of the volume performed earlier in the week, you may perform the same, or more, volume of throws and jumps- as one example only.
I should also note that the lower the volume is on the second session the more favorable it is to ensure that the distance of the sprint reps are on the longer end relative to the block.
So, if 0-30m is the range and day one was 360-390m then day two would consist of 180-216m or 195-234m, respectively. In either case, I’d suggest that the session consist of all 30m efforts and as such you’d get a total of 6-8 x 30m which is fine for a GPP session; particularly if the volume of throws and jumps were to increase on that day.
Lastly, since the example you referenced is GPP we must remember that we may disperse additional intensive elements across all training days so there’s more opportunities to get some stimulus that you may be concerned of missing via a substantial reduction in sprint volumes on the second speed day.