Backup file much smaller than expected
I have been using Acronis home version for a number of years and versions. My C drive is 500GB and used space generally stays around 35-40%. Used space, as shown in disc properties, has been around 195GB used for a while now. My backups used to reflect this in that the file size for a full disk backup was probably around 120-130GB, if I recall properly. However, my C backups have shrunk to 70-some GB in the past couple of months, and I am wondering why. I think it cooresponds with my upgrading to A2019, though I'm not certain. Perhaps Acronis 2019 has a more highly compressed coding or something? I just want to make sure that it's not skipping something important.
I used WizTree this morning to look at my C drive file allocation. The ~195GB shows there as well, and the only rough correspondence I can make out to the smaller backup is that system info and other files without extensions show as taking up 49% of the used space, about 90GB. I'm way out of my league here, but would appreciate any explanation or clarification.