System Log Event IDs 15 and 16 Source Kernel-General Windows 10 Pro

Question

I notice some Event ID 15 that say for example:

Hive \??\GLOBALROOT\Device\HarddiskVolumeShadowCopy23\WINDOWS\System32\config\SYSTEM was reorganized with a starting size of 30355456 bytes and an ending size of 18423808 bytes.

And some Event ID 16 that say for example:

The access history in hive \??\Volume{54d1ef8b-a0cc-11ea-9d70-b682885f3a74}\System Volume Information\SPP\SppCbsHiveStore{cd42efe1-f6f1-427c-b004-033192c625a4}{77CE6431-72B1-4795-B1D7-91CE7874FF9F} was cleared updating 7236 keys and creating 553 modified pages.

Just curious what those mean... I don't seem to have any system problems at the moment but an curious what those messages are telling me.

Is Windows performing some kind of routine maintenance cleanup procedure?
Is it some kind of Scheduled Task that runs and if so which Task would that be?
Do these events occur at any specific time like on a schedule, on startup, on shutdown, when Windows thinks it needs it, etc.?