Quotas times less than 10 minutes?

Absolutely not a supported feature, not tested, don't complain to support, etc.  But yes.

cc get http quota_time_slice

cc set http quota_time_slice 5

If you do this, I highly recommend going to every policy that uses quota, checking and re-saving the policy.

Thank you so much.

Do you know if these settings are captured in the system backups, just in case there are any issues?

AFAIK yes it should be in backup but not positive and not tested.

Same with upgrades.  There is no reason that an upgrade would have to touch that value but for some reason it did, it could be reset.