Counting heads up with the dealer vs counting with other players

Should I count the same way I would with other players at the table if I'm heads up with the dealer? Normally I count the dealer's up card first then I start counting the player's second card as it comes out. So would I count the dealer's card first then add up my hand or if I can should I wait for all three cards to be flipped over then try to count 3 at a time? Does it matter with a fast dealer vs a slow one? I haven't played much head's up yet. On CVBJ I try to count all 3 at one time but I'm just not sure what is the best way or how most AP's do it.
Common wisdom is to count each player hand when the second card comes out, it lets you "cancel" a high and low card in the same hand. As for the dealer's card, it doesn't really matter so long as you count it, and don't count it twice. If you're counting the dealer's card first, great. Keep doing that.