Any ideas on which program you use?
250,000MB at 30MB per second (reasonable USB 2.0 maximum) -> 8333 seconds -> 139 minutes -> 2h19m. Assuming some imperfections, call it 3 hours. That's way less than 17, for copying
the entire drive, at
USB 2.0 speed.
If it's taking that long, there's something about the interfaces and/or files and/or device(s). With mostly small files, FI, HDDs are just plain slow, and your best bet is to not copy them a lot. They have a physical arm that has to move around a lot, and that takes time, and can bring you down to <2MBps, sometimes. There might be ways to work around it, but choosing another program is not going to change it by much,
if it's doing the same copying. The program you use has only a small effect on the speed. You need to change what you copy, or what your storage medium is.
To that end, you can try any program that is made to
sycnhronize, such as Karen's Replicator (with the right settings), Synctoy, Syncback, or any number of others I can't think off off the top of my head at this moment. That way, only the initial copy takes a long time, while subsequent uses just copy what has changed.