Reason of Non-Generation of Statistics Summary

I wish to know what could be the causes of Squid not generating
Statistics Summary. I have experienced that even when the capacity of
the disk space alloted for the cache logs is still in working level,
Squid at times skip days of generating these statistics summary.
I wonder if the Virtual Memory has something to do with it?

Thank you in advance.

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  Mervin B. Manangan
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