It's an unquantifiable subjective element.
For me, I probably value light bolt throw and close over a nebulous "smoothness" quality, but I tend to incorporate that when I talk about "smoothness".
I personally don't like running the bolt hard and/or fast, and a light bolt lift and close really suits my personal style.
But it's all subjective.
I guess this is really more of what I was getting at.
I dont compete, so I never run a bolt hard or fast, I just want that whole process as "smooth" as possible.
Right now, my "smoothest" feeling action is a worked over 700 VLS in 243AI. Bolt lift sucks but it does have the factory adjustable trigger so there's that. (Change is coming) It's right around 2.5lbs and breaks decent enough for the occasional varmint/predator control it sees.
Cock on close is .018"
Pin fall is .258"
My smoothest overall action would be my 700LA in 300winmag. It's probably an 80's, or maybe even a late 70's vintage reciever, so round count is who knows. I picked it up used from a friend of mine and he probably took it in trade for something else. I've put roughly a thousand rounds through it myself since I've owned it over the last 10-12 years. It has a jewell trigger in it around 1.25lbs, and has the best bolt lift/close of my three 700's.
Cock on close is worst of the three at .025"
Pin fall is also the worst at .265"
Last up is the roughest of the bunch lol. 700 LTR. Also a worked over, this time by myself. It's just kind of rough all the way around.
Bolt lift is smooth, but a touch on the stiff side, closing it feels like it hits a detent that you have to push through. It has a triggertech primary set at the minimum 1.5lbs. Gretan firing pin assembly.
I did send the reciever to black canyon customs to have primary extraction corrected and also had the bolt handle welded.
Cock on close for this one is the best at .005" and pin fall comes in at .259"