Often I come across drives having smart issues or reallocated sector count exceeded. In such cases disk gets detected but gives error while copying or cloning.
One of the tool I have supports CLEAR SMART / CLEAR P-LIST & CLEAR G- LIST / G To P transfer.
Other way we can use N1 command in terminal.
How critical is this command for Seagate drives? Can I use it for all seagate drives or specific ones? Erasing P-list could be disasterous for Data.Can someone please help.

When in actual cars a signal glows, or on OBD you see 'service needed' you go on the net and find ways to reset the error or turn off light. Until something wonderful happens...
Is this the scenario ?

Any other suggestion please.

This was a real suggestion but either you don't want to hear it or simply don't know how to use it :

if SMART triggered or something happened there must be a reason , so a COMPLETE DIAGNOSE must be done.

Example : one head is physically damaged during drive activity due to bump or structural failure, in the time before the drive becomes unstable there is time to try reallocation of "bads" (not really bads, only the head could not read it) and maybe trigger SMART, but the drive is unstable.

Would you reset SMART in this case with a non completely working head ? No wonder you get an error because the drive was unable to init SMART data with other damage too.

Of course the question would have been pointless if you know how to get data regardless of SMART status, overcoming the problem.
But don't pretend to repair a car with only a screwdriver = to do miracles with terminal commands only.
So the answer is NOT to fiddle with commands on unstable drive UNLESS YOU ARE 10000000000% SURE about the drive condition and what the problem is.

BlackST - Appreciate your detailed technical explanation. I am very new in firmware recovery & dont have any expensive tools.
from various posts in hddguru forum ,I think we can test heads by H command ,if no led message comes up heads are ok.
In case when heads are ok and only reallocated sector count is high can we use N1 command or erase G-list?
Thank you

Just save everything of SA and rom before applying modifications in case doesn't work properly. Hard to do without tooling or k-h...
I see almost everyday ruined drives / garbled data after applying 'internet fixups'.