ReadyNAS 314 - a year of hell and now lost 10years of data!

Disk 4 seems to be cloning ok - well it has definitely been running for a lot longer than disk 2 managed, and there's only the infrequent clickedy-click coming from it.

Here's the status at the moment:

GNU ddrescue 1.16
Press Ctrl-C to interrupt
rescued:    13600 MB,  errsize:    513 GB,  current rate:        0 B/s
   ipos:   442674 MB,   errors:     841,    average rate:     447 kB/s
   opos:   442674 MB,     time since last successful read:      11 s
Copying non-tried blocks...

Is this good, bad, gonna take much longer?

What goes up and when? is 513GB of errors going to go downwards as it recovers stuff, do I need to run the other 11 commands that dorp the skip size down and do it in reverse? (that's another 11 runs through!) Does it get quicker on each pass as it only has to try the bad parts? Do I have to many to make it worthwhile? etc...

Here's what is currently still running from this morning:

ddrescue -r 1 -a 10485760 -b 4096 -d -f -K 65536 /dev/sdb /dev/sdc /mnt/hdd0/btrfsd4log.txt           (sector size=4096, forced, min readrate=10485760, skip size=65536, retries=1)

Here's what is left to run!:

ddrescue -R -r 1 -a 10485760 -b 4096 -d -f -K 65536 /dev/sdb /dev/sdc /mnt/hdd0/btrfsd4log.txt       (and again in reverse)
ddrescue -r 1 -a 10485760 -b 4096 -d -f -K 16384 /dev/sdb /dev/sdc /mnt/hdd0/btrfsd4log.txt            (skip size down to 16384)
ddrescue -R -r 1 -a 10485760 -b 4096 -d -f -K 16384 /dev/sdb /dev/sdc /mnt/hdd0/btrfsd4log.txt       (and again in reverse)
ddrescue -r 1 -a 10485760 -b 4096 -d -f -K -A 4096 /dev/sdb /dev/sdc /mnt/hdd0/btrfsd4log.txt          (skip size down to 4096, retry all failed/skipped sections)
ddrescue -R -r 1 -a 10485760 -b 4096 -d -f -K -A 4096 /dev/sdb /dev/sdc /mnt/hdd0/btrfsd4log.txt     (and again in reverse)
ddrescue -r 1 -b -d -f -K 1024 /dev/sdb /dev/sdc /mnt/hdd0/btrfsd4log.txt                                                  (skip size down to 1024, no min readrate)
ddrescue -R -r 1 -b -d -f -K 1024 /dev/sdb /dev/sdc /mnt/hdd0/btrfsd4log.txt                                             (and again in reverse)
ddrescue -r 1 -b -d -f -K 256 /dev/sdb /dev/sdc /mnt/hdd0/btrfsd4log.txt                                                    (skip size down to 256)
ddrescue -R -r 1 -b -d -f -K 256 /dev/sdb /dev/sdc /mnt/hdd0/btrfsd4log.txt                                               (and again in reverse)
ddrescue -r 1 -b -d -f -K 64 /dev/sdb /dev/sdc /mnt/hdd0/btrfsd4log.txt                                                      (skip size down to 64)
ddrescue -R -r 1 -b -d -f -K 64 /dev/sdb /dev/sdc /mnt/hdd0/btrfsd4log.txt                                                 (and again in reverse)

If someone could give me a quick run-down of the process and what I would see in numbers that would be great.