As GM I tend to write down the parry splits for the NPCs first, then ask the PCs to declare, the DB and OB are then inferable from results in resolution, but might change round to round, so the players often don't depend on them. . .though a smart player will infer total ob+db and thus the maximum swing. . .i.e. if someone does 40 OB and 30 DB in round one, you can guess that they can't do more than 70 OB or 70 DB, which could lead to calculating your round 2.
As a player, I'll often be somewhat conservative in DB round 1, then once I know they have at most 70 (i.e. in the first 10 seconds of high parry I assess how good they are in a fight) I then declare based on that.
If I have 140 OB, I then go 70/70 and they are screwed likely. . .but if I only have 35 skill, this might be the moment to start to worry I've bitten off more than I can chew and start full parrying and hoping one of the other PCs will come stab this guy in the back.