IMHO you should really have started a new thread, as your issue is not related to that of the OP. Anyway, comments below...
robin hood wrote:
I'm attempting a data recovery on a damaged Seagate hdd using getdataback, and I have a limited grasp of what's actually going on.
That is a fundamentally flawed approach - copy individual files from a "damaged" disk, unless you are prepared to take the risk that things will get worse and/or that the s/w being used won't cope with such a disk. That seems to be the situation here .

It would help if you explain your analysis as to why & how that drive is "damaged". Do you mean it has been physically damaged e.g. dropped or something else?
robin hood wrote:
So I attempted a copy of a file from the damaged drive to another external hdd. It worked fine initially but upon hitting the 20% mark the transfer froze and while I left it for a few minutes, I decided to close the program and run it again more prepared.
Likely that the s/w encountered slow or unreadable sectors, which caused the "freezing".
robin hood wrote:
It's a 1TB external drive so I know that's not uncommon, but what did I do the first time to speed the process up?
I'm not in front of your system, so I have no idea... This is another problem with DIY - inadequate logging of process, so unable to explain it to other later on.

My guess is that you might have done nothing different, and the change in behaviour is due to deterioration in the source disk drive itself.
robin hood wrote:
Any advice would be extremely welcome.
Consider carefully if you have the skills to carry on, and whether you want to take the risk of further deterioration. Your attempts could be making successful recovery more difficult (= more expensive) or potentially impossible, if significant damage is being done to the platter(s).
If you want to continue (i.e. data not worth recovery cost, and you are prepared to lose everything), then search for recent posts here on cloning software. I personally wouldn't use Windows cloning software (*nix s/w, while less friendly, is more usable IMHO, but it still needs skill & experience to get the best results). The best cloning results are typically with the source (faulty) disk direct attached via SATA (the target can be USB attached, if desired). Then attempt to clone the whole source (faulty) disk to a new (target) disk of the same size or larger. Then you may need to use data recovery s/w to extract data from the target disk, if the filesystem on that target disk is badly damaged, due to there being unreadable filesystem metadata on the source.
Using getdataback at
that stage, on a fully working disk (but perhaps with filesystem corruption), would be one option.
That's a typical DIY process, but as I said, there are risks and your story so far raises particular concerns that the drive might be deteriorating. Alternatively, you may want to consider getting pro help. I hope those suggestions are useful, but I'm not promising to hand-hold through the whole process.