DavidR - I get what you are saying but shouldn't there still be a sequence of stream subfolders like that shown in your post #23 - all things being equal?
No not really, as the image in Reply #23 the last released VPS was 19011206. Once a new VPS (19011506) was somehow released. The Avast housekeeping (should have) cleaned up all previous stream updates as they would automatically be included in the new 19011506 VPS release.
Now we would start to see new 19011506_stream sub-folder for the new streaming updates as the date changes you could well see a new 190116(or 17)06_stream sub-folder/s created (as in the image in Reply #32). Currently this isn't a usual situation, so no one can say with certainty exactly how the defs and stream update sub-folders will be structured (until we are also getting regular regular VPS Updates).
Another annoying thing is with the subfolder getting so large the streaming refs are hard to spot - at the bottom of a long list is pkg.....399bin but the latest ones are pkg......3e0.bin the 3 is fixed but the sequence goes last digit 0-9 then changes to a-f then the e will change to f . There are now 993 items in the sub folder.
Unfortunately the naming convention isn't strictly numeric (as I'm guessing here), as file naming conventions would normally be of a certain size, so just using numeric would stretch or break a limited file name convention. Currently my last check shows there are now 1070 objects in that stream sub-folder.
If you want to check easily, create a shortcut desktop icon to the defs folder and change the order they are displayed to Date Modified.