"Time left calculation" values are always wrong. There are too much dependencies which influences the real value.
The copy process consists at least of :
- reading the file entry from FAT
- reading the first block of source data
- writing the file entry to FAT
- writing the first block of destination data
- reading the 2nd block of source data
- ...
For several small files you have to read the FAT entries very often, which results in slow transfer rates.
Even the time for a single big file will vary:
- First KBytes will be transfered very fast (while filling the file cache) and the rest is transfered normal.
- Writing a file in an uninterrupted sequence to free sectors is much faster than spreading into parts all over the harddisk
Further more, your copy process is not the only one who accesses the disk. Other processes such as antivirus and even Windows is interrupting your transfer always but not constantly.
All programs I found are just rough guessing the time with variations of -100 to + 100 percent, which is not worth the effort IMHO ...
Just to mention the installation program saying "Time left: 2 sec" and staying another 3 minutes on the screen
