During COVID I have been trying to donate platelets every week. The Red Cross requires at least 7 days between donations.
It is a pity that this minimum spacing cannot be every 6 days. I can really only donate on weekends, Saturday and Sunday. But if I donate on Sunday one weekend I cannot donate on Saturday the next week - too close. The only way I can switch back to donating on Saturdays is to miss a week.
Does it really make that much of a difference?
--
Imagine that on even weeks I can donate on Saturday but on odd weeks I can good donate on Sunday. With the 7 day rule the number of donations I can make is reduced by 33%, compared to being able to donate every week as would be allowed if the separation were 6 days. That's more than the 1/7th you might naïvely expect.
Such phenomena of quantization are common in computers. E.g. on P6 our 4 cycle FP multiplier and 3 cycle FP adder shared a pipeline. If we had not stretched the latency of the adder to 5 cycles we would have lost a lot of compute bandwidth.