Im pretty generous on concedes when playing 1on 1 On a easy straight putt, Ill concede 4fts, If Im more than 1 up, I may concede 5-6ft putts if I know they are straight and all second putts ( even if you run it 15ft past hole, Ill concede it to keep you from having a chance at 3putt.
On tough putts like pin high on 15 bethpage though, you are putting anything over 2ft lol
When I'm playing alt shot its a little different as you dont want to piss off a partner by giving lots of generous concedes and then lose the match. Personally, I never ask for concedes. I setup and try to make everything ( even rush on the short ones to try to beat them conceding just for sport.
But I will generally even with a partner, I'll give everything inside of 3-4ft unless its for them to WIN the hole or match ( then just concede anything under 2ft)
I know Im pretty complicated and it would be hard to type all the my rules ahead of time. So if they give it, yay, if not , no worries, Ill still give them a 4 ft putt even if they make me putt my 1.2 footers.