I have been using CCleaner for about a year. When I used it to wipe free space it took about 90 minutes to do a simple overwrite and continuously gave percentage of time remaining to complete the task.
Recently , however ,I noticed two things:
It doesn't give an accurate estimate of time left to completely wipe the free space(the time remaining jumps around)
and when I look at % completion it goes to 80% to 90% and after 100% it starts all over and goes to 5%, 10% , etc.
I have to cancel the disk wipe manually or it might never stop