Time Machine Help

Why don't you take a look for yourself? Time Machine backups are easily browseable in the Finder.

Perhaps using a program like WhatSize on your Time Machine volume would help.

 

How big is your Time Machine partition? How much data are you backing up? How often do you add or modify files?

A portion of a 160GB drive isn't going to last long if you work with large files (either downloading or modifying them).

Files that will only last 3 days are clearly ones that you use frequently, so you should know when you'd want to revert those. It'll keep at least one backup copy of every file you've selected. It'll keep multiple copies as space allows.

 

Have you excluded anything?

I excluded both the Safari and Firefox caches

Right click time machine -> Time Machine Preferences
Click on Options
Hit the plus sign on bottom left

If you have Firefox, use the finder to go to
<your user>/Library/Caches/Firefox/Profiles/a26r2rhu.default/

Then add the Safari Cache directory
<your user>/Library/Caches/Safari

This will avoid you saving all the web pages / images that you surf all day. They take up a lot of space. My firefox cache was 85MB, Safari was another 19 MB.

I would do this for any other data you don't need to save, such as RSS feed caches, etc.

 

If the file hasn't changed, what difference does it make? Yesterday's copy will be the same as the three week old copy will be the same as the six month old copy. Why would you need multiple copies of the same unchanged file?

If your drive is filling up after a day, you're either doing something wrong or committing changes to several gigabytes each day. It will store as many copies as space allows. Your unchanged files will remain in backup and your oldest copies of the frequently changed files will be deleted to make room for the current changes.

I'm not seeing the problem, except that you should buy a bigger drive if you want to be able to store multiple copies of frequently changed large files.