Time Machine Question

I recently started using Time Machine to back up my VM's and have a general question to see if I'm doing something wrong. From reading the documentation, it's saying that a snapshot of the VM is generated every 48 hours (using default settings), which is is what's backed up rather than TM backing up the entire VM every hour.

The issue that I'm having is that I'm backing up anywhere between 8 and 20gb an hour rather than every 48 hours. While that could be considered "good" from a disaster recovery standpoint, obviously if you do the math, I'm going to zero out my TM disk at some point and then it'll start trimming backups to continue backing up. While I know that's an eventuality anyway, I would rather be efficient in backing up rather than eat up the space quickly for no reason.

I couldn't get the attachments button to actually allow me to upload a file, but a screen cap of my backup settings for my VM is at http://sdrv.ms/YURp1E . Can anyone give me some direction as to what to do?

BTW - shortly after I started writing this post, TM started it's backup, which is the first since 1030am yesterday. 43GB in total. This is atypical of what I normally get (8-20gb) but just wanted to throw that in there...

Thanks in advance